Texas Longhorns star Andrew Jones picked up right where he left off nearly 2 years ago ... balling out in his first game with significant minutes since battling leukemia.

The 21-year-old was leading the team in points when he was diagnosed with cancer in January 2018. He underwent several rounds of treatment ... and was adamant he would return to the hardwood.

Jones briefly made 2 appearances last season, but proved he was officially BACK in Tuesday night's season opener against Northern Colorado ... dropping 20 points in 29 minutes in UT's win.

Not only was it a great performance ... it was Jones' CAREER HIGH!!!