Grandson of legendary actor Jackie Gleason.
His mother's name is Linda Miller, sister's name is Jennifer, brother's name is Jordan and half-brother's name is Joshua John Miller, who is an actor and author.
When his best friend Kiefer Sutherland broke off his engagement with Julia Roberts in the early '90s, Julia ran off to Europe with Jason, and the two were eventually a couple.
Attended Saint Monica Catholic High School in Santa Monica, California.
Turned down the lead role of Mitch Mcdeere in The Firm (1993), the role then went to Tom Cruise.