Adrian Peterson was busted for DWI Thursday night in Minnesota ... where the Vikings legend was booked into the county jail, even posing for a mug shot.

TMZ Sports has learned the former league MVP was pulled over at 3:20 AM in an Audi Q5 ... after a state trooper says they saw AP speeding, going 83 in a 55 MPH zone.

The cop suspected Peterson, 40, was drunk ... and when the future Hall of Famer ultimately submitted a breath sample on the scene, he blew a .14.

FYI, the legal limit is .08 in Minnesota.

Adrian, who played 10 seasons for the Vikings and is one of the team's greatest players, was booked into the Hennepin County Jail on 4th-degree DWI ... before he was ultimately released.

Thursday was supposed to be a joyous day for Peterson -- he was a featured guest at the team's draft day extravaganza at U.S. Bank Stadium, where thousands celebrated the big night.

Several hours after leaving the party, Peterson was in cuffs.