Ritchson was born in Grand Forks, North Dakota, the son of Vickie (born June 21, 1958), high school teacher and David Ritchson (born June 5, 1956), a retired U.S. Air Force chief master sergeant. He is the middle of three brothers; Eric, the oldest, and Brian, the youngest. During his childhood, his family moved to Rantoul, Illinois. At age 10, Ritchson's family settled in Niceville, Florida. He attended Niceville High School and graduated in 2001. In a 2013 interview with Indonesian magazine Da Man, he stated that he once obtained a full music scholarship. From 1999 to 2003, he attended as a dual-enrollment student and graduated with an Associate of Arts degree at Okaloosa Walton Community College, now Northwest Florida State College. He was a member of the Fine Arts division's Soundsations and Madrigal Singers.
He began his modeling career in the Abercrombie and Fitch catalogue; he also modeled underwear for the men's online underwear store internationaljock.com. In 2008, he was signed to Los Angeles agency Vision Model Management and appeared on N2N Bodywear. By early 2009, Ritchson made his final appearance in his modelling career for Abercrombie and Fitch.
Alan Ritchson first came to the attention of the public in 2004 when he appeared on American Idol as one of the top 87 contestants in the third season before being cut in Hollywood. His appearance on the show was noted for his striptease in one episode in which he wooed judge Paula Abdul.
His television acting credits include a recurring guest star role on the television series Smallville as Arthur Curry, a.k.a. Aquaman, a small role as an army officer in the 2006 Hallmark Channel movie Though None Go with Me alongside Cheryl Ladd, and the role of Lucian Manet in the 2009 Lifetime original film Nora Roberts' Midnight Bayou. His role in Smallville marked the first time that an actor portrayed Aquaman in an officially licensed live-action production. His Smallville co-star, Justin Hartley, has since portrayed Aquaman in an unaired pilot of the same name. Ritchson reprised his role as Aquaman for a cameo appearance in the animated film: Justice League: The New Frontier, and the final season of Smallville. In 2009, he appeared on a third-season episode of Starz's Head Case in which he played a male stripper. Ritchson also made an appearance on CSI: Miami, in which he played a dead victim in episode 19 of season 8. In 2011, he appeared in an episode of season 3 of 90210 as a love interest for main character Teddy Montgomery (Trevor Donovan). He played Thad Castle in Spike TV's Blue Mountain State as a captain on a college football team, until the show was cancelled in February 2012, after its third season. In 2015, Ritchson is a current regular on the NBC variety show I Can Do That (based on Israeli variety show) alongside Nicole Scherzinger, Ciara, Joe Jonas, Cheryl Burke and Jeff Dye, and hosted by Marlon Wayans. In 2016, he appeared in "Nosedive", an episode of the anthology series Black Mirror.
Movie credits include a role in the 2006 film The Butcher, as well as a minor role in 2009's Fired Up! In 2007, director Robert Zemeckis used Ritchson for his facial image, physique and movement for actor Ray Winstone of the title character of Beowulf.
Ritchson portrayed Gloss, a tribute in the 75th Hunger Games, in The Hunger Games: Catching Fire (2013). Ritchson also portrayed Raphael in Teenage Mutant Ninja Turtles, a reboot to the Teenage Mutant Ninja Turtles film series after the four previous films. He returned to his role as Thad Castle in the Blue Mountain State movie, Blue Mountain State: The Rise of Thadland. Ritchson co-starred in Rooster Teeth Production's first feature-length movie—the science fiction comedy Lazer Team in January 2016.
Other projects include an independent album called This Is Next Time, released in late 2005 and appearing in a Russian commercial for Orbit gum. Alan also appears in a web series entitled, "Enormous Friends" with his Blue Mountain State co-star, Rob Ramsay.
AlbumsThis Is Next Time (2006)