Seau was known for his passionate playing style, including a fist-pumping dance he performed after big plays. He was praised by teammates for his work ethic and leadership. He would play when hurt, and often refused to leave games. "He played the game the way it was meant to be played," said retired Denver Broncos quarterback John Elway.

Seau married Gina Deboer in 1991 and divorced in 2002. They had three children together, a daughter and two sons.

He died of a self-inflected gun shot wound at the age of 43.