The Hall of Fame coach retired from football Tuesday, three days after the end of an emotionally trying season that included the fatal shooting of safety Sean Taylor.
Gibbs, whose 2-year-old grandson was diagnosed with leukemia last January, stepped down with one year remaining on his five-year, $27.5-million contract. Redskins owner Daniel Snyder was unsuccessful in his attempts to persuade Gibbs to stay, talking to him until the early hours of Tuesday.
"My family situation being what it is right now, I told him I couldn't make the kind of commitment I needed to make," Gibbs, 67, said during a news conference at team headquarters in Ashburn, Va.
He added of his family: "I felt like they needed me."
The coach, who also served as team president, spent a total of 16 years with the franchise in two stints, guiding the Redskins to four Super Bowls and winning three. In his second go-round with the team, he was 31-36, including 1-2 in the playoffs.
"I hate to leave something unfinished. I made an original commitment of five years. I felt bad about that," Gibbs said.
"It's one of the few times in life I felt like I walked away from something. But I also felt like . . . 'Hey, I need to be in a different situation.' "
No decision has been made on a successor, although current assistant coaches Gregg Williams and Al Saunders are expected to be the leading candidates. Williams is a former coach of the Buffalo Bills; Saunders coached the San Diego Chargers.
Former Pittsburgh coach Bill Cowher has also been mentioned in news reports as a possible candidate, although he previously said he planned to sit out another season before returning to coaching.
Gibbs owns a NASCAR team, Joe Gibbs Racing, which is run by son J.D. Gibbs.
"Obviously, it'll be great to have him back here on a regular basis," the younger Gibbs said in a written statement. "It's a biased opinion because he's my dad, but there's so much that he brings to the table. He has such a gift for leading a team."
In what some people believe was the coaching performance of his career, Gibbs helped his players refocus after the November killing of Taylor, the team's best player, and directed them to the playoffs.
The Redskins, who won their final four games of the regular season to go from 5-7 to 9-7, lost in a wild-card game Saturday at Seattle.
In a recent interview with the Washington Post, Gibbs said it has been difficult lately to keep his focus on football.
"It's one of those things, when you're closing in on the end of your life at some point, it's not going to be, 'I wish I spent more time coaching a football team,' " he said. "It's going to be all the things you missed."