Luke Timothy Grimes was born on January 21, 1984, in Dayton, Ohio. His mother is Angie Grimes (née Barker), and his father is the Reverend Randy Grimes. Luke has three older brothers and sisters.

In 2002, Luke graduated from Dayton Christian High School, after which he moved to New York, where he graduated from the American Academy of Dramatic Arts.

The actor's big-screen debut came in 2006, in the film All the Boys Love Mandy Lane; since 2009, Grimes has appeared in television series.