Breckin went to grade school with Drew Barrymore and attended Beverly Hills High School with Alicia Silverstone, Joshua John Miller and Brandon Williams. It was Barrymore who introduced Breckin to her agent, after which he started doing commercials and the game show Child's Play.

After being accepted to California State University at Northridge, Breckin decided to put school on hold and pursue acting. He has always wanted to be a kindergarten teacher and may still do that in the future. Breckin was the drummer in the Streetwalking Cheetahs with his brother, Frank, which recorded a demo in 1995. He was the lead vocal on two songs, "Carnival" and "Dave". During 1995-1996, the band played about 10 gigs around Los Angeles. The Streetwalking Cheetahs' second album, "Overdrive" and their new album, "Live on KXLU", feature songs written when Breckin was still in the band. These songs include "None of Your Business", "All I Want", "Peppermint", "Thought that Crosses My Mind" and "Turn Me Down". After the Streetwalking Cheetahs, he started his own band, Bellyroom, with Seth Green and Alexander Martin, Dean Martin's grandson. They played a few gigs around Los Angeles in 1996. Currently, he doesn't play in any band.

Breckin's friends include Josh Holland (USA High) and Seth Green. His best friend is Ryan Phillippe, with whom he starred in 54. Breckin is married to Deborah Kaplan, who wrote and directed Can't Hardly Wait, in which Breckin had a cameo.

Breckin's hobbies include playing drums, video games and sometimes sports. He's a big fan of Sean Penn, Robert De Niro, Al Pacino and Richard Dreyfuss. He spends most of his free time with Kaplan, and also with Seth Green and Ryan Phillippe.
His parents, Chris (a management consultant) and Dorothy (a microbiologist-turned-travel agent), are divorced. Has an older brother Frank and a younger brother Adam. Drew Barrymore's teen biography "Little Girl Lost", credits Breckin as having given her her first kiss at age 10 while Breckin was age 11. Is in business with Seth Green and Ryan Phillippe. These three actors have their own production company. Played the drums in a punk band with a few friends. Actress Miriam Shor, who played the role of "Julie Hermann" in the TV series Inside Schwartz, tutored Breckin Meyer, who is not Jewish, on playing the Jewish character "Adam Schwartz". Has a daughter with wife Deborah Kaplan, named Caitlin Willow, b. December 31, 2003. Went to the same High School as Angelina Jolie, Michael Klesic, Nicolas Cage, Corbin Bernsen, Lenny Kravitz, David Schwimmer, Jonathan Silverman and Richard Dreyfuss. Was in a deleted scene from Old School, in which he played a police officer. Only a glimpse of the scene can be seen in the blooper reel on the DVD.