Robbins was born in West Covina, California to a liberal Irish-American Roman Catholic family. He moved to Greenwich Village with his family at a young age while his father, Gil Robbins, pursued a career as a member of the folk music group The Highwaymen. Robbins joined Theater for the New City at age twelve, participated in the drama club at Stuyvesant High School, spent two years at SUNY Plattsburgh and then returned to California to attend drama school at UCLA.

Upon his graduation in 1981, Robbins founded the Actors' Gang, an experimental theater group, in Los Angeles with actor friends from his college softball team. He also took small parts in films, such as the role of frat animal "Mother" in Fraternity Vacation (1985). His breakthrough part was pitcher "Nuke" LaLoosh in the 1988 baseball movie Bull Durham.

He received critical acclaim for his starring role as an amoral movie executive in the 1992 film The Player. His directorial and screenwriting debut was 1992's Bob Roberts, a mockumentary about a populist right-wing senatorial candidate. Robbins then starred alongside Morgan Freeman in the critically acclaimed The Shawshank Redemption based on Stephen King's short story.

Since that time, Robbins has written, produced, and directed several films with strong political content, such as the critically-acclaimed capital punishment saga Dead Man Walking in 1995, based on the book by Helen Prejean, which earned him a directorial Oscar nomination, and 1999's Depression-era musical Cradle Will Rock. Robbins also continues to act in mainstream Hollywood thrillers, adding shades to his usual affable characters like Arlington Road (1999) as a next door neighbor with evil intentions, and Antitrust (2001) as a malicious computer tycoon. Robbins continues to act in and direct Actors' Gang theater productions.

Robbins won the Best Supporting Actor Oscar and the SAG Award for his work in Mystic River (2003), playing a traumatized adult victim of child molestation. In 2005, he won the 39th annual Man of the Year Pudding Pot Award given by the Hasty Pudding Theatricals of Harvard. His most recent acting roles include a menacing ambulance driver in director Steven Spielberg's War of the Worlds and an appearance in director Jon Favreau's Zathura; both films were released in 2005.

In early 2006, Robbins directed George Orwell's novel 1984 for Actors' Gang at their new location at The Ivy Substation in Culver City, California.

Robbins lives in New York City with actress Susan Sarandon (with whom he has been involved since their meeting on the set of Bull Durham in 1988) and their three children. He is a prominent spokesperson for anti-globalization, and has vocally opposed the 2003 invasion of Iraq.

In 2003, a 15th-anniversary celebration of Bull Durham at the National Baseball Hall of Fame was cancelled by the Hall of Fame's president, Dale Petroskey, who was on the White House staff during the presidency of Ronald Reagan, stating Robbins' public questioning of the president and the war represented "a danger." Durham co-star, Kevin Costner, defended Robbins and Sarandon, saying, "I think Tim and Susan's courage is the type of courage that makes our democracy work... Pulling back this invite is against the whole principle about what we fight for and profess to be about" (see [1]).

After Robbins and Sarandon attended the Academy Awards ceremony in 2003, Robbins threatened to punch The Washington Post journalist, Lloyd Grove. Robbins objected to the fact that Grove, while on assignment, had interviewed Sarandon's mother, Leonora Tomalin, a conservative Republican. Tomalin went on record speculating that Sarandon and Robbins had politically "brainwashed" her grandson, Jack Henry (who was born in 1989). In his article, Grove quotes Robbins as saying "If you ever write about my family again, I will fucking find you and I will fucking hurt you." (Source: Grove, Lloyd, March 25, 2003), "Night of the Livid Celeb", Washington Post, page C01). Sarandon's mother was once quoted as saying that despite her obvious political differences with her daughter, she feels "Susan is a good mother".