Savage was born in Glencoe, Illinois, the son of Joanne F., a consultant, and Lewis M. Savage, an industrial real estate broker. His brother is actor Ben Savage and his sister is actress/musician Kala Savage. His grandparents were Jewish immigrants from Latvia, Ukraine, Germany, and Poland, and Savage was raised in Reform Judaism. In 1999, he graduated from Stanford University, where he was a member of the Sigma Alpha Epsilon fraternity, with a degree in English. On August 7 2004, Savage married Jennifer Lynn Stone. They have a son named Oliver Philip Savage, who was born on August 5 2006, and a daughter Lily Aerin Savage, who was born on May 3, 2008. He is also a fan of the band Phish, being spotted at Madison Square Garden for the band's 1998 new year's show.
In 1988, Savage appeared as Kevin Arnold on The Wonder Years, the role for which he is best known. His tenure in the show resulted in two Golden Globe Nominations and two Emmy Nominations for Outstanding Lead Actor In A Comedy Series; at the age of 13 he would be the youngest actor ever to receive these honors. He would remain on the show until it went off the air in 1993. During this period, he appeared in several movies, most notably Little Monsters, Vice Versa, and The Wizard. After The Wonder Years, Savage primarily did guest and supporting roles, including an appearance on the show Seinfeld as himself, the show Boy Meets World (which starred his brother Ben) and in the film Austin Powers in Goldmember as 'Number Three'.
He has also lent his voice to several animated projects, including Kim Possible, Justice League Unlimited, Oswald, and Holidaze: The Christmas That Almost Didn't Happen. His two lead roles since The Wonder Years were on the short-lived sitcoms Working and Crumbs.
Savage has also appeared as a serial rapist on Law and Order: Special Victims Unit and as a womanizing professor on Boy Meets World. He ranked at #27 on VH1's 100 Greatest Kid Stars.
Besides directing several episodes, Savage co-produced the Disney Channel Original Series Phil of the Future. In 2007, he was nominated for a Directors Guild award for the Phil episode "Not-So-Great-Great Grandpa".
Savage made his theatrical film directorial debut on 2007's Daddy Day Camp, which earned him a nomination for "Worst Director" at the 28th Golden Raspberry Awards. Savage has also directed several episodes of It's Always Sunny in Philadelphia.