EXCLUSIVE

Bad news for Kansas City Chiefs tight end Demetrius Harris ... dude just got sentenced to JAIL TIME after getting caught with more than an ounce of weed.

As we previously reported, Harris was pulled over in Missouri back in March 2017 and, during the stop, cops found more than 35 grams of marijuana in the car.

He was initially charged with felony possession -- but later struck a deal with prosecutors in which he pled guilty to a lesser possession charge (misdemeanor) and in exchange he got 2 days in jail.

A spokesperson for Bates County Circuit Court tells TMZ Sports Harris will not get credit for time served -- he must complete the 2-day sentence at a later date. No word on when he plans to turn himself in.

Harris was also sentenced to 80 hours of community service and 2 years probation and must complete an NFL drug program.

Once again ... all of this for WEEEEEEEEED.