England prop White has been plagued by neck and shoulder injuries since the RBS 6 Nations opener against Wales in February but made his comeback for the Tigers' trip to Headingley.
The 31-year-old was sin-binned for his part in an early scuffle with Mark Regan - and the Tykes went on to record a shock 23-22 victory over the league leaders.
The kicking of Gordon Ross - another Lions hopeful - proved crucial for the Tykes as the fly-half racked up 18 points.
Leicester had looked to have taken control of a tense contest with a try early in the second half from Leon Lloyd but battling Leeds hit back with a spectacular solo effort from Tom Biggs.
The Tigers, who had been off-colour all afternoon, had a chance to snatch victory when Leeds conceded a stoppage time penalty.
However Andy Goode, who had already kicked 15 points for the Tigers, failed to hold his nerve and put his kick wide to hand Leeds a most unlikely victory.