The Redskins announced the move Monday. Gruden, 52, posted a 35-49-1 record in six years with the franchise.
"Through the first five games of the 2019 season, the team has clearly not performed up to expectations, and we all share in that responsibility," the Redskins said in a statement.
"Moving forward we are committed to doing all that we can collectively as an organization to turn things around and give our Redskins fans and alumni a team they can be proud of in 2019 and beyond."
The New England Patriots beat the Redskins 33-7 Sunday at FedEx Field in Landover, Md. Gruden told reporters after the game that he had not been told anything regarding his job security.
"Nobody told me anything and I don't have a concern," Gruden said. "I'll just wait and see. If the key works on Monday, I'll keep working. Go attack the Miami Dolphins and plan on getting our first win next week."
Washington went 7-9 in each of the last two seasons. The Redskins were 4-12 in 2014, Gruden's first season. Washington turned it around for a 9-7 mark and a playoff appearance in 2015 before going 8-7-1 in 2016.
Gruden entered the NFL as an offensive assistant for his brother, Jon Gruden, with the Tampa Bay Buccaneers in 2002. He was the offensive coordinator for the Cincinnati Bengals for three years before joining the Redskins.
Washington has the fifth-worst offense in the NFL, in terms of yards per game. The Redskins are averaging the third-fewest points, but are allowing the third-most points, per game.
The winless Redskins face the winless Miami Dolphins at 1 p.m. EDT Sunday at Hard Rock Stadium in Miami.