Zorn was informed of his dismissal shortly after the team returned to Redskins Park following Sunday's season-ending 23-20 loss at San Diego.
Zorn went 12-20 over two seasons, but he lost 18 of his last 24 games after a 6-2 start in 2008. The Redskins struggled early despite a weak schedule this season and finished 4-12, their worst record since 1994.
"The status quo is not acceptable," general manager Bruce Allen said in a statement released by the team. "I felt it was necessary to not waste a moment of time to begin building this team into a winner."
Zorn's replacement will be Washington's seventh coach since Snyder bought the team in 1999. Playing a role in the decision will be Allen, who was hired as the GM last month.
Zorn's dismissal had been expected for months. The front office stripped him of his play-calling duties in late October, and Snyder has interviewed assistant coach Jerry Gray for the job weeks ago, according to the Fritz Pollard Alliance, which monitors minority hiring in the NFL.
Former Denver Broncos coach Mike Shanahan is considered the favorite to replace Zorn. The new coach, Snyder and Allen will have a monumental task to rebuild a team with many roster deficiencies and major questions at offensive line, quarterback and running back.
This year's team has been hurt by numerous injuries, a lack of depth and many off-the-field distractions, but also by an inability of Zorn's West Coast offense to consistently find the end zone.
The Redskins failed to score more than 17 points in their first eight games, prompting the front office to bring longtime NFL assistant coach Sherm Lewis out of retirement as an offensive consultant and play-caller.
Zorn, who had never previously been a head coach or coordinator in the NFL, wasn't even on Snyder's list of candidates when Joe Gibbs retired at the end of the 2007 season. Zorn become a last-minute option when other contenders either showed no interest, dropped out or were deemed unsatisfactory. Snyder initially hired Zorn to be the offensive coordinator, then promoted him to head coach two weeks later after an extensive interview.