Chiefs WR De'Anthony Thomas cut a deal with prosecutors to close out his weed case this month ... and as part of the agreement, he had to admit he possessed drugs.
The NFL player was busted for speeding in Allen County, Kansas, back on Jan. 26 ... and when officers pulled him over, they said they smelled a "burnt odor of marijuana."
When cops searched the car ... they say they found weed and arrested the 26-year-old.
Thomas was hit with charges of marijuana possession and speeding and was facing up to 6 MONTHS in jail if he was convicted on the weed charge.