Thomas was charged with felony marijuana possession at his Minnesota apartment in March.
Vikings running back Rob Thomas was suspended for three games on Tuesday after violating the NFL's substance-abuse policy, the league confirmed.
Thomas was arrested on felony marijuana charges in January after police found over 143 grams of the drug at his Minnesota apartment. The 23-year-old is still eligible to participate in Vikings training camp, and he can still play in preseason contests.
The Jacksonville State product joined the Vikings in 2018 as an undrafted free agent. He appeared in five games for Minnesota last season, tallying 30 yards on eight carries.
Thomas will miss the first three games of Minnesota's 2019 campaign. He will be eligible to return to the field against the Bears on September 29 after missing matchups against the Falcons, Packers and Raiders.