Thenmozhi (Anushka Shetty) arrives in Boston to meet her niece. While leaving for Chennai, in the airport, she gets a free upgrade and sits next to Sathyadev (Ajith Kumar). During the flight, she starts vomiting due to overeating and with Sathyadev's help she feels better, so she develops a crush on him. The next day in Chennai, Sathyadev and Thenmozhi are at a cafe, when a criminal named Victor (Arun Vijay) comes to abduct Thenmozhi, but fails due to Sathyadev subduing him.
Then the film goes back to Chennai 1989 (then known as Madras) where Sathyadev's father (Nassar) is killed by a criminal. From there Sathyadev makes a decision and a few years later he is seen in a jail with Victor. With both of their help they escape from jail, get Victor married to Elizabeth alias Lisa (Parvathy Nair), and meet Matthew (Stunt Silva), a criminal. There Sathyadev infiltrates the gang as an IPS officer, kills Matthew and injures Victor. Then in an attempt to stop a gangster he meets Hemanika (Trisha Krishnan) who needs to get to a hospital due to her being pregnant. Two years later, he meets Hemanika and her child Isha (Baby Anikha). After seeing each other for four years they decide to get married with Isha's approval. On the day of their marriage, Hemanika is killed; both Sathyadev and Isha are heartbroken. Years later Sathyadev decides to quit and travels with Isha around India along with his colleague Richard's (Vivek) help. After he returns, his neighbour's children have gone missing and he discovers Victor is now helping his boss, Muruganandham (Suman), stealing organs illegally with foreign doctors to help him. Sathyadev is able to find both the children, and is also able to find their next target, Thenmozhi. Then it goes back to the present where Sathyadev keeps Thenmozhi in their house with Isha.
In an attempt to get Thenmozhi, Victor and his team kidnap Isha and is held captive along with Lisa who is also helping out. Victor said he will give Isha if they give Thenmozhi, which Sathyadev accepts. Then when they arrive at the location, they find Muruganandham and kill him. Then he finds where Thenmozhi is and saves her and Isha despite killing Lisa.
A few days later, Victor sneaks into Sathyadev's house and reveals himself as Hemanika's killer. The duo engage in a fight which ends with Sathyadev victorious; he drags a wounded Victor outside and leaves his colleagues to kill him.
At last Isha and Thenmozhi plan out the birthday of Isha. Thenmozhi promises to be there throughout the day. Before Sathyadev takes Isha home, he reminds Thenmozhi of the pending coffee that Thenmozhi wanted to have with Sathyadev, indicating that he is ready to move on life with Thenmozhi.
In October 2013, producer A. M. Rathnam signed up Ajith Kumar for another film following their collaboration in Arrambam (2013) and director Gautham Menon was confirmed to direct the project. Sridhar Raghavan, who wrote the script for the Bollywood film, Dum Maaro Dum (2011), was also signed by the team to assist Gautham Menon with film's script. Thiagarajan Kumararaja is also credited for the screenplay. Harris Jayaraj was signed on as composer, despite early speculations that A. R. Rahman would work on the film.
Anirudh Ravichander had hinted about himself working in the film, but his inclusion remained unconfirmed, and ultimately proved to be untrue. Australia-based cinemtographer Dan Macarthur was selected to do the film's cinematography. On 29 October 2014, Suresh Chandra, Ajith's agent, confirmed the title for the film to be Yennai Arindhaal (English: Well, if you know me...). The title is a play on "Unnai Arindhaal", a song from Vettaikaaran (1964). The title of the dubbed Telugu version was announced as Entha Vaadu Gani (English: No matter how strong the opponent is...) along with few poster designs on 23 November 2014.
Anushka Shetty was signed on by the team to play one of the leads, despite early suggestions that Pallavi Subhash had been selected for the film. Prior to the official announcement of the cast, several actors were linked to portray the role of the antagonist in the film including Karthik and Prashanth. Actors Aadhi, Arun Vijay and Arvind Swamy were also reported to be part of the cast, though the latter denied signing the film. Aadhi also clarified on not acting in the film. In mid-April 2014, Arun Vijay was confirmed to portray the film's antagonist and had started filming his portions.
On 18 April 2014, comedian Vivek joined the cast, collaborating with Gautham Menon after the director's first venture Minnale (2001). Bangalore based Amit Bhargav was selected to play the role of Anushka's beau in the film. On 15 May 2014, Trisha was officially cast as another lead of the film, collaborating with Gautham Menon for the second time after Vinnaithaandi Varuvaayaa (2010). Her role was later confirmed as the wife of Ajith's character. Actor Arun Vijay was chosen to play a supporting role. Ajith's salary was reported to be around ₹25 crore (US$3.9 million) for the film. Parvathy Nair was cast in a role paired opposite Arun Vijay, making this film the second she signed in Tamil, after the later-released Uttama Villain. Daniel Balaji played a cameo, thus becoming a part of all films in Gautham Menon's cop trilogy. Nassar made a cameo appearance as the father of Ajith's character.
Menon stated that details regarding the film would be unveiled by the end of August 2014. As per his statement, Menon later said that Ajith would appear in four different looks in the film, and Anushka would portray an IT professional in the film. Trisha said that her portion in the film would have a more intense love story than her last outing with Gautham Menon, Vinnaithaandi Varuvaayaa (2010). She further said that though Ajith had been playing commercial films off late, this film would show him in a radical avatar that she herself would love to see him in. It was confirmed that Ajith would be sporting black hair, a thick moustache and a slimmer look in the portions involving Baby Ankitha and Trisha, whereas he would appear in his natural grey hair style in the portions involving Anushka. According to sources, Ajith would be seen riding a Bullet Bike in the film. Stills featuring Ajith sporting a bearded look were released in early October 2014. In November 2014, Vivek confirmed that his character — a police officer — would be a rather serious character with only a subtle sense of humour.
A. M. Rathnam issued an official statement confirming that the film would be launched on 9 April 2014 and a ceremony was thereafter held to mark the beginning of the project. The first filming schedule subsequently began on 11 April 2014 near the VGP Universal Kingdom theme park near Chennai. The first schedule was completed after 12 days of shooting in Chennai, during which an action sequence was filmed.
The second schedule began shooting on 14 May 2014. A lot of night time shooting was said to have taken place in the film, especially in Mount Road. Shooting also took place in Malaysia. Dan Macarthur confirmed that the second schedule was completed by the end of May 2014. A wedlock scene between Ajith and Trisha was canned in the last week of July 2014. Shooting continued in Chennai along the ECR stretch up to the first week of August, during which the portions involving Baby Ankitha were completed. In the second week of August 2014, about 75% of the filming was reported to be completed and a few scenes, including a train sequence, were shot in Hyderabad. A scene featuring Ajith and Trisha and background artists was filmed in a theatre.
Filming moved to Rajasthan where a song sequence was shot in segments in Jaipur, Jodhpur and Jaisalmer for 10 days. A romantic song, "Mazhai Varapoguthey", which featured Ajith, was shot in September 2014. Filming then proceeded in Sikkim, where a "lullaby" song sequence featuring Ajith and Baby Ankitha was shot. The final schedule of filming began at Hyderabad again, where filming continued for 15 days. By late November, the shoots of all the songs have been done and a fight sequence was shot in Binny Mills in Meenambakkam, Chennai. A solo song with Trisha was also completed. In early December, shooting of the climax chase sequence was done in guerrilla film-making mode in some busy roads of Chennai without the knowledge of the public. Shoot of climax fight sequences began on 8 December 2014. Few key scenes were shot at Hyderabad Railway Station in mid December 2014. Later few patchwork scenes were shot at Chennai for 3 days with which principal photography came to an end.
The film was shot entirely on the Arri Alexa digital motion picture camera system.
Gautham Menon described Yennai Arindhaal as the third in his franchise of police films after Kaakha Kaakha (2003) and Vettaiyaadu Vilaiyaadu (2006), and the last of the trilogy. He also described Ajith's character Sathyadev as an "extension" of the protagonists in the first two films.
The film's soundtrack album and background score were composed by Harris Jayaraj. The soundtrack album consists of seven tracks. All but one song had lyrics written by Thamarai.
In July 2014, Harris recorded a romantic song sung by Karthik. Harris said that he had recorded a fresh voice from the United Kingdom for the first song in the film, which was planned to be similar to "Karka Karka" from Menon's Vettaiyaadu Vilaiyaadu (2006). In August 2014, Harris started recording the third song for the film. On 18 September 2014, he updated that 3 songs were completed. It was also known that Trisha's character would have a solo song.
In response to the request by Ajith's fans, the makers agreed to release a single track prior to the soundtrack release. The "mass number" "Adhaaru Adhaaru" sung by Vijay Prakash and Gana Bala, the only song that did not feature lyrics by Thamarai but Vignesh Shivan, was released as the lead single on 11 December 2014. Within hours of its release the track topped the iTunes Indian songs chart. On YouTube, the single track got over 30 thousand hits in 24 hours and was liked by more than 7 thousand viewers. Harris Jayaraj confirmed via Twitter that "Adhaaru Adhaaru" was a gangster song and not Ajith's introduction song in the film.
Harris Jayaraj was busy working on the final mix of the OST in early December 2014. It was confirmed that the score and the songs would be done in Dolby Atmos surround sound system. The audio rights were purchased by Sony Music and the album was released on 1 January 2015. Within hours of its release, the soundtrack topped the iTunes Indian albums chart. The album received positive reviews from critics, with The Hindu stating that the music repeated the magic of his last collaboration with Gautham Menon, which was Vaaranam Aayiram (2008).
The satellite rights of the film were sold to Jaya TV. The film was earlier expected to be released in January 2015. But Gautham Menon confirmed that the audio launch would take place in November 2014 and the film was planned for a December release. On 22 November 2014, it was confirmed that the film would be released on 15 January 2015, during the festive occasion of Pongal, but the film was again postponed to 29 January, due to delays in post-production. and later to 5 February. The film was dubbed in Kannada as Sathyadev IPS and was released in 2017.
The film had featured in the Behindwoods list of the "Top 10 most anticipated films of 2014", before its release was delayed to 2015.
In March 2015, the website Herotalkies.com (VS Ecommerce Ventures) legally released Yennai Arindhaal online in Full HD 1080p with English subtitles, but only for audiences who live outside India.
Trisha's first look in the film was revealed in mid-August 2014, where she was seen on the sets sporting a saree. Another still of the actress was made available on 29 August 2014. The film's title and first look poster were reported to be revealed in August 2014, on Ganesh Chaturthi. However, a still featuring Ajith in his black haired look was released instead, where he was pictured riding a Royal Enfield Bike. More stills featuring Ajith and the other cast and crew members were released on the same day. The first teaser trailer was released on 3 December 2014, and gained over 5 lakh views within 12 hours of its release on YouTube. The teaser received over 95000 likes in YouTube, the highest number of likes for a South Indian film, in just over a day. The teaser later went on to cross 55,000 likes in three days. The teaser became the most-liked Indian film teaser, which was previously held by Bang Bang! (2014) with 61,429 likes at that time. Sony Music released the Telugu version of the teaser on 8 December 2014.
The teaser has crossed 5 million views on YouTube, becoming the second South Indian film after 'I' to cross this mark, and has received a 92,000 plus likes so far.
Nicy V.P of The International Business Times rated the film 4 stars out of 5 and wrote "Yennai Arindhaal is one of the classiest movies of Ajith and Gautham Vasudev Menon is back with a bang with this entertainer". Karthik of CNN-IBN rated 4 out of 5 and stated "Ajith kumar as the cop, the gangster, the father and the lover will win you over". M. Suganth of The Times of India gave 3.5 stars out of 5 and wrote "it does seem less punchy than Kaakha Kaakha and Vettaiyaadu Vilayaadu but the film belongs to Ajith and the star is in such fine form here". IANS gave 3.5 stars out of 5 and wrote, "Despite some tonal and length issues, Gautham impresses mostly in Yennai Arindhaal, and gives this tale of a police officer a much need emotional tug". Karthik Subramanian of The Hindu wrote "Performances lift an otherwise predicatable fare from Gautam Vasudev Menon". Another reviewer from The Hindu, Sudhir Srinivasan, wrote, "A rushed climax, a problematic organ trafficking angle, a repeated plot device, a predictable ending… and yet Yennai Arindhaal comes as a breath of fresh air...There's just that one melisaana kodu (thin line) that stops it from being terrific". A third reviewer from that site, Udhav Naig, wrote that "the final installment of Gautham Vasudev Menon’s cop trilogy...is a much-needed intervention in the Tamil commercial cinema space. It is also the most engaging of the three".
Sify wrote that the film was "watchable" for "Ajith’s majestic screen presence and the underlying emotional current". Rediff gave 3 stars out of 5 and wrote, "The backdrop of Yennai Arindhaal is new and the plot is engaging, but the characters, the situation, and even the dialogues are reminiscences of director Gautham Menon's previous cop films". Indiaglitz rated the film 3.25 out of 5 and wrote "Gautham Menon Class delivered by Ajith’s Mass screen presence". Behindwoods.com rated the film 3 out of 5, calling it "Gautham's movie with Ajith adding colour admirably".
This film has been nominated under five categories for 63rd Britannia Filmfare Awards (South).Filmfare Award for Best Actor – Tamil – Ajith Kumar
Filmfare Award for Best Supporting Actor – Tamil – Arun Vijay
Filmfare Award for Best Supporting Actress – Tamil – Parvathy Nair
Filmfare Award for Best Music Director – Tamil – Harris Jayaraj
Filmfare Award for Best Lyricist – Tamil – Thamarai (for "Unakenna Vaenum Sollu")
As of November 2015, Menon has completed writing half the script for a sequel to Yennai Arindhaal.