The Vikings wanted Winfield, who was due to make $7.25 million in 2013, to restructure his contract, sources told ESPNTwinCities. But the three-time Pro Bowler refused to take a pay cut, according to the report.
Winfield, 35, started 15 games last season and recorded three interceptions for the Vikings. A 14-year veteran, Winfield had 21 interceptions in nine seasons with the Vikings.
General manager Rick Spielman confirmed the moves shortly after the NFL market officially opened Tuesday.
The Vikings also reached an agreement with wide receiver Jerome Simpson on a one-year contract, a league source told ESPN.
Simpson, 27, appeared in 12 games last season with the Vikings, hauling in 26 catches for 274 yards.
The Vikings brought back Simpson one day after trading Percy Harvin to the Seattle Seahawks, a deal that is contingent on the star wideout passing a physical and agreeing to a new contract, according to sources.
A five-year veteran, Simpson was suspended for the first three games of last season for violating the NFL's substance abuse policy.
The 6-foot-1 Simpson has 97 catches for 1,278 yards and seven touchdowns in 41 career games with the Vikings and Cincinnati Bengals. A 2008 second-round draft choice, he enjoyed his best season in 2011, when he had 725 receiving yards and four touchdowns with Cincinnati.
Information from The Associated Press was used in this report.