Chiklis was born in Lowell, Massachusetts and grew up in Andover, Massachusetts. His Greek American paternal family hailed from the Greek island of Lesbos. He is fluent in Greek, Italian and Spanish.

A natural performer, Chiklis began entertaining his family with celebrity imitations when he was just five years old. As a child, Chiklis appeared in regional theater productions and earned his Equity card at age 13. He later attended Boston University School of Performing Arts where he received his BFA.

On the day of graduation, Chiklis hopped in his car bound for New York City. Upon arriving in the Big Apple, Chiklis later admitted that he "was going to kick this city's ass." But only a few years later and following the route of the struggling actor, Chiklis said he was sitting on the Brooklyn Bridge begging for forgiveness. It was on that same day, after auditioning for the part almost a dozen times over two years, he got the part of John Belushi in the controversial movie Wired in 1989. Despite critical praise for his performance, the film was panned in general and it flopped at the box office. He has also guest starred in several popular series such as Miami Vice, L.A. Law, Murphy Brown, and Seinfeld alongside bit parts in films like Nixon. He was the star of a critically-panned NBC sitcom called Daddio which proved to be short-lived.

He is best known for starring in two popular, but highly different, police television series: The Commish (1991-1995) and The Shield (2002-). The The Commish was a family friendly police comedy/drama in which Chiklis played Anthony 'Tony' J. Scali, a police commissioner in a small city in upstate New York. A stern but lovable father figure, Chiklis's character had an easy going style, smart wit, and an unorthodox approach to parenthood and police work.

After playing Curly Howard in a television movie about the Three Stooges he decided to reinvent his image. With his wife's help he spent six months on an extensive workout regimen and shaved his head. He turned up to audition for The Shield looking nothing like the pudgy, friendly character of The Commish. Instantly winning over the creator Shawn Ryan, Chiklis nabbed the leading role of the show's tough, edgy, detective Vic Mackey. Although The Shield has been controversial because of its violent content, Chiklis's acting has been highly praised and he has won several awards for his role. Playing the role of the bulked up and brutal cop has also helped Chiklis break out from type-casting, shedding the overweight and friendly image that had defined his career in the past.

Since 2000 he's also taken up a number of voice roles, voicing Chihiro's father, Akio, in the English dub of Hayao Miyazaki's Spirited Away and Roman/King Webster in the direct-to-video feature The Adventures of Tom Thumb & Thumbelina. He's also done several episodes of Family Guy and had a voice role in Heavy Gear: The Animated Series.

In 2005 he starred in Fantastic Four as The Thing, and is slated to return in 2007 for the sequel. A fan of the comic series, he informed his brother Peter when he was 18 that if there was ever a movie made of the Fantastic Four, he would play Ben Grimm.