Ninjutsu master Hamato Yoshi (Splinter) is carrying his four pet turtles through the streets of Manhattan when he encounters members of an alien race called the Kraang. During an altercation with these aliens, Yoshi and the turtles are exposed to the Kraang's chemical, called mutagen, which causes organic beings to undergo major physical transformations. Yoshi takes on characteristics of a brown rat and the turtles take on human characteristics. Yoshi retreats to the New York City sewers where he raises the four turtles as his sons and imparts to them his knowledge of ninjutsu.
Now teenagers, the turtles (Leonardo, Raphael, Donatello and Michelangelo) venture to the surface for the first time and learn that the Kraang are using the mutagen as part of their plan to take over New York City. They befriend the teenage April O'Neil after she and her psychologist father Kirby are abducted by the Kraang. Donatello, who has developed a crush on April, is able to rescue her. While Kirby remains a prisoner of the Kraang, April becomes an ally of the turtles, who try to help her locate her father. April is also trained by Splinter to be a kunoichi, a female ninja.
After learning of Splinter's and the turtles's presence in New York, Splinter's adoptive brother and long-time enemy Oroku Saki (Shredder) travels there from Japan and orders his birth clan, the Foot to track down Splinter and his sons, and put an end to their clan. This family feud eventually earns the coincidence of two of Shredder's disciples, martial arts star Chris Bradford and Brazilian street thug Xever Montes, getting mutated into Dogpound (later Rahzar) and Fishface. Learning about the Kraang's presence through his adopted daughter Karai, Shredder enters an alliance with the aliens to destroy their mutual enemies in the Hamato Clan.
The turtles later discover that the Kraang came to Earth from Dimension X and built their headquarters with a company called T.C.R.I and are plotting to use the mutagen and a set of Kraang-like powers that April was born with to convert Earth into a planet suitable for their race. After the turtles rescue Kirby, the Kraang invade New York, but the turtles and April emerge triumphant when they send the Technodrome, the Kraang leader Kraang Prime's ship, crashing into the sea. Meanwhile, Splinter battles Shredder and learns that Karai is his own daughter, Hamato Miwa, who was kidnapped by Shredder and who believes that Splinter killed her mother. The season ends with turtles celebrating their victory over the Kraang as Splinter hides the secret of Miwa from them.
The turtles struggle to contain an outbreak of mutations that occurs thanks to the leftover mutagen from the thwarted Kraang invasion. Kirby is among the victims of the outbreak, and a misunderstanding leads April to become very upset and ashamed of the turtles and break off their friendship. However, the turtles are able to earn her forgiveness when they save her from Karai, who has taken temporary command of the Foot while the Shredder is away in Japan. Along with April came her new friend Casey Jones, who helps repel an assault on the turtles' lair. Kirby is eventually restored to his human form when Donatello manages to concoct another Kraang chemical called retro-mutagen, which causes organic beings to reverse their major physical transformations, and help keep it away from former T.C.R.I inventor Baxter Stockman, who gets mutated into Stockman-Fly while under Shredder's employ.
Meanwhile, Shredder returns from Japan with the mutated Japanese bounty hunter Tiger Claw as his new second-in-command. Tiger Claw is later sent through a portal to the 1987 cartoon universe, but returns.
During a battle with the turtles, Karai is informed of her true nature by Leonardo (who has developed a crush on her since season 1), but she is too reluctant to accept it. When she is taken to the lair, she finally realizes the truth and disowns Shredder, who responds by imprisoning her. Repeated attempts to free Karai ultimately succeed, but Shredder captures her again and uses her as bait to kill the Hamato Clan. However, Karai ends up mutated into a serpent, to everyone's horror.
In response to this, Shredder has the Foot Clan help the Kraang, who have just perfected the previously unstable mutagen, launch a second invasion of New York, starting by destroying the turtles' lair and forcing them to abandon it. The Kraang begin mutating New York's populace, including Kirby, despite the efforts of Earth's military and the turtles. Leonardo is gravely wounded when he is ambushed by the entire Foot, and Splinter is seemingly killed during a battle with Shredder. The turtles, April, and Casey are forced to flee to the O'Neil family's summer home in Upstate New York as the Kraang successfully conquers Manhattan.
The group takes refuge at the O'Neil family's summer home in North Hampton in order to recuperate from their loss at the hands of the Kraang and the Foot Clan. Leonardo takes an extended amount of time to recover, but guided by an apparition of Splinter, is able to overcome his physical and mental wounds. They eventually return to New York with the goal of finding Splinter, Karai, Kirby, and their other missing allies and liberate the city from the Kraang. They are successful in finding Splinter and set up a temporary base in the abandoned Antonio's Pizza, and Donatello begins work on new samples of retro-mutagen as the search for Kirby and Karai continues.
Meanwhile, Shredder mutates Russian arms dealer Ivan Steranko and his only known disciple, high-tech master thief Anton Zeck, into Bebop and Rocksteady for stealing his helmet, the Kuro Kabuto, and hunting Karai in exchange for a safe departure from the Kraang-invaded city before sending them to find her again. The duo succeed behind the Turtles's backs and Shredder promises to cure Karai of her misery. The turtles, on the other hand, run into the a recently founded mutant team called the Mighty Mutanimals (consisting of mutant allies that they made during the last two seasons, such as Slash, Leatherhead, Pigeon Pete and former British neurochemist Dr. Tyler Rockwell) who are backed by their human ally Jack J. Kurtzman. Together, they manage to banish the Kraang back to Dimension X and free New York, but the effect of the invasion eventually earns Shredder cemented control of the city's criminal underworld for his efforts to create a mind-control serum meant for the turtles, Mutanimals and Karai.
The turtles are later offered by future time sorceress Renet to time travel to the past, where they meet up with a younger Hamato Yoshi and Oroku Saki, as well as Yoshi's late wife and Karai's mother, Teng Shen. During the battle between Yoshi and Saki inside the burning Hamato Clan dojo, Shen is accidentally killed by Saki, who meant to kill Yoshi instead. Saki leaves the dojo after his hair burns off from the fire and kidnaps Yoshi and Shen's baby daughter Miwa, vowing to raise her as Karai and leaving Yoshi to die. After his escape, the turtles save Yoshi, as they were "always destined to" before traveling back to the present with Renet.
When the Kraang return to Earth, the Turtles discover that the Kraang have another enemy from Dimension X in the form of the Triceraton Empire. Despite their best efforts and Shredder violating the Foot Clan's temporary truce with the Turtles by stabbing Splinter during the fight, the ruthless Triceratons activate the Heart of Darkness, a black hole-creating machine which annihilates both the Kraang, the Earth, and everyone on it. But just as it comes to the worst for the Turtles, April, and Casey, they are rescued by a friendly robot by the name of Professor Honeycutt (aka the Fugitoid) who uses a spacecraft to take the Turtles, April and Casey to a journey into space.
After the Turtles, April, and Casey are saved from the destruction of Earth, the Fugitoid uses his spacecraft the Ulixes to turn back time to six months earlier in order for him and the Turtles to prevent the Triceraton Empire led by Emperor Zanmoran from assembling the three components of the Heart of Darkness that are scattered throughout the universe before everything on Earth is lost. Besides fighting the Triceratons, the Turtles also face new enemies in outer space like Lord Vringath Dregg of the planet Sectoid and the bounty hunter Armaggon, and even have an adventure with their interdimensional 1987 counterparts and their enemy Krang who is an exiled relative of Kraang Subprime. Despite the efforts of the Turtles, the Triceratons are still able to collect all three pieces of the Black Hole Generator, only for the Turtles to return to Earth and join forces with their past selves to warn Splinter before he is killed by the Shredder, stop the detonator of the Heart of Darkness, and defeat the Triceratons. The Fugitoid destroys the Black Hole Generator near the Triceraton spacefleet, causing to explode, presumably killing the Triceratons. In the aftermath of the fight against the Triceratons, the past versions of the Turtles, April, and Casey leave Earth with the past Fugitoid in the Ulixes while the present Fugitoid's head reactivates in Earth's orbit.
Weeks later following the Triceraton Invasion being thwarted and the Foot Clan's disappearance, April is promoted to kunoichi at the time when the witch Shinigami arrives and is revealed that she is Karai's friend as they plot to rebuild the Hamato Clan and dispose of Shredder who is still recuperating from his last fight with Splinter. While Karai and Shinigami got some ninjas on their side, the Foot Clan strengthens the Footbot army by creating the Elite Footbots. Furthermore, some other crime organizations have been plotting to take over the Foot Clan's territory and a crystal shard of unimaginable power which April received from the alien Aeons during their space adventure is beginning to exert a baleful influence on her. Using a special mutagen formula made by Stockman-Fly, Oroku Saki recuperates and becomes Super-Shredder in order to take back control of the Foot Clan. Once a stable formula is made, Super-Shredder attacks the Turtles, the Mighty Mutanimals, Karai, and Shinigami which ends with Splinter falling in battle against Super-Shredder and is buried at the O'Neil family's summer home in North Hampton. This leads up to the final battle at Super-Shredder's hidden mansion where Leonardo manages to slay Super-Shredder and throw his mutated Kuro Kabuto to the other Turtles in victory.
Following the death of the Super-Shredder, Tiger Claw has led the unspecified Foot Cultists into obtaining the Scroll of the Demodragon and a special control amulet called the Seal of the Ancients that would enable him to summon the demodragon Kavaxas. When Kavaxas is summoned, Tiger Claw plans to use Kavaxas' wish-granting abilities to revive the Shredder. Upon demonstrating the revival ability on Rahzar who fell in an underwater battle against Leatherhead, Kavaxas states that he will need the Kuro Kabuto that contains Shredder's mental energies. Upon Rahzar and Tiger Claw reclaiming the Kuro Kabuto after Kavaxas drained the soul out of Shredder's former right-hand man Hattori Tatsu, Kavaxas states that they will need the Shredder's heart for the revival to occur.
On November 22, 2015, Nickelodeon aired a 2D animated special, Half-Shell Heroes: Blast to the Past. In the special, the Ninja Turtles are accidentally transported back to the Cretaceous period by an ancient meteorite and must work together with Rocksteady and Bebop (along with some newly befriended dinosaur allies) to get back to their own time, while simultaneously fending off would-be predators and a faction of the Triceraton Army led by General Zera. Random House also released a book based on the special while Playmates released new dinosaur toys in the fall to coincide with the program. The special was seen by 1.41 million viewers. It was released on DVD, through Nickelodeon and Paramount Home Media Distribution, on March 15, 2016.
On October 21, 2009, a press release was made indicating that Viacom had bought the complete rights of the Teenage Mutant Ninja Turtles franchise from Peter Laird for $60 million, and would be developing a CGI animated TV series for its Nickelodeon family of channels for broadcast in 2012. A feature film, released by Paramount Pictures (also a division of Viacom), debuted in 2014.
Jason Biggs originally voiced Leonardo and Rob Paulsen voices Donatello. In June 2011, it was confirmed that Sean Astin is playing Raphael and Greg Cipes is Michelangelo. In August 2011, it was revealed that Mae Whitman would be the voice for April O'Neil. In April 2012, it was announced that Phil LaMarr would be playing the role of Baxter Stockman and Nolan North would be playing a race of aliens known as the Kraang, while Roseanne Barr is confirmed to voice their leader, Kraang Prime. Actress Kelly Hu confirmed her role as Karai in May 2012. Corey Feldman was confirmed to play the role of Slash. Recurring TMNT character Casey Jones began appearing in the second season, and is voiced by former Nickelodeon star Josh Peck.
Production art was leaked on the Nickelodeon website before it was taken down. The images showed the designs of all four turtles, Shredder, Splinter, a teenage April O'Neil and the Kraang, an alien race that combines elements of both Krang and the Utroms. A trailer for the series was released on June 21, 2012, on Nickelodeon USA. In June 2014, it was announced that Seth Green would replace Jason Biggs and Dominic Catrambone as the voice of Leonardo in season 3.
The series has also been released to home video, mainly on DVD. Nickelodeon's typical Region 1 DVD release schedule is to release each season across three volumes, consisting of four DVDs total, with each disc containing 6-7 sequential episodes.
Similar to the Teenage Mutant Ninja Turtles Adventures series from Archie Comics, IDW Publishing released a spin-off comic title named New Animated Adventures featuring original adventures, starting July 2013. The series was cancelled after 24 issues, and was succeeded by a revised story program entitled Amazing Adventures, which was launched in August 2015. One of the main reasons for this revision was the inclusion of the Shredder as a vital character into the comic stories, which had been neglected in New Animated Adventures.
Playmates Toys created a new line of Teenage Mutant Ninja Turtles consumer products to go along with the show.
In mid 2012, Playmates Toys released their first wave of basic Teenage Mutant Ninja Turtles action figures which consisted of "hero figures" Leonardo, Donatello, Raphael, Michelangelo, Splinter and April O'Neil as well as "villain characters" Shredder, Kraang, and a Foot Soldier. In early 2013, Playmates released series 2 which consisted of the new "hero" character Metalhead as well as new villains Dogpound and Fishface. In April 2013, the third wave appeared which included the "hero" character Leatherhead as well as villains Snakeweed and Baxter Stockman. Wave four was released in early August and it featured the villains Rat King and Spyroach as well as new "Stealth Tech" versions of the four turtles. Wave 5 was released in October with a 7 pack of Mousers as well as four baby versions of the Turtles (Turtles in training) October saw the final release of 2013 with wave six which included two new villains: Spider Bytez and a newly sculpted Shredder figure featuring a removable helmet and cape. Wave seven first appeared in February 2014 with figures for Kirby Bat, Squirrelanoid, Casey Jones, and Mutagen Man.
The Lego Group released a Lego theme of Teenage Mutant Ninja Turtles in 2013.
in July 2014, Build-A-Bear Workshop released a series of plush versions of the Turtles, as well as other TMNT themed apparel including an outfit of Shredder, along with items such as the Turtles' signature weapons.
In April 2014, Diamond Select Toys unveiled the first series of Minimates mini-figures based on the cartoon. Two unpainted promotional figures were given away at Comic-Con International 2014, and Series 1 was released in fall 2014 as blind bags at Kmart and comic shops, and in 2-packs at Toys "R" Us. Each location had one or two exclusive characters in addition to their shared characters. Series 2 was released in comic shops in spring of 2015 and at Toys "R" Us in summer 2015, again with both shared and exclusive figures. Series 3 is scheduled for both locations for the fall of 2015. A Series 4 has been confirmed.
In 2013, Nickelodeon released Teenage Mutant Ninja Turtles: Rooftop Run for iOS devices such as the iPhone, iPad, and iPod Touch.
On August 28, 2013, Activision released Teenage Mutant Ninja Turtles: Out of the Shadows, a downloadable 3D beat 'em up game, for Xbox 360 and Microsoft Windows. On April 15, 2014, a version was released for the PlayStation 3. The game features an online multiplayer co-op for up to four players.
Activision also released a Teenage Mutant Ninja Turtles video game based on the series for Wii, Xbox 360, and Nintendo 3DS on October 22, 2013.
On September 4, 2014. Activision announced there being a second game based on the show called Teenage Mutant Ninja Turtles: Danger of the Ooze. The game was released on October 28, 2014 for the Nintendo 3DS and Xbox 360, and the PlayStation 3. The game was developed by WayForward.
The series premiered on Canadian channel YTV on September 29, 2012. It also premiered on Nickelodeon (UK and Ireland) in the UK and Ireland on October 1, 2012. It premiered on Nickelodeon (Australia and New Zealand) in Australia and New Zealand on October 8, 2012. In India, it airs on Teen Nick India. It premiered on Nickelodeon Canada in Canada on September 2, 2013. It also airs on Channel 5 in the UK.
IGN has given the show positive reviews, with many episodes reviewed being given the "Editor's Choice" title. "Invasion" has received the highest rating of 10/10. The series premiered in the U.S. to 3.9 million viewers.
Variety has praised the show, saying "...handsomely produced effort, with a strong vocal cast, considerable humor and scads of high-spirited action. If the goal was to introduce the Turtles to a new generation — amphibious mission accomplished."