Ken Jennings was born in Edmonds, Washington, a Seattle suburb, on May 23, 1974. His father was an international lawyer, and he spent 15 years of his childhood in South Korea and Singapore, where his father worked.

Mindy is his wife. Dylan, their son, was born in November of 2002. In November of 2006, they welcomed a daughter.

Jennings and his family are Latter-day Saints members of The Church of Jesus Christ of Latter-day Saints.