The Redskins' decision, which was announced Monday, means Griffin will make $16.2 million in 2016. He will make $3.27 million in base salary this season.
The Redskins had until May 3 to pick up the option, which is guaranteed for injury only, meaning Washington could release Griffin prior to the start of the 2016 league year without any salary cap ramifications.
But the Redskins have publicly supported Griffin throughout the offseason despite the former Heisman Trophy winner's disappointing first year under coach Jay Gruden.
Despite previously indicating that he would hold an open competition for the starting quarterback job, Gruden reversed course at the NFL scouting combine in February, saying the Redskins would enter the season with Griffin "as our No. 1 guy."
Griffin appeared in just nine games last season due to an ankle injury, passing for 1,694 yards and four touchdowns with six interceptions. He has battled injuries and widespread scrutiny since his outstanding rookie season in 2012, when he led the Redskins to the NFC East division title.
ESPN.com Redskins reporter John Keim contributed to this report.