The on-loan Chesterfield forward buried a low, angled drive under visiting goalkeeper Seb Brown's body 12 minutes into the second half to cement Oxford's place in the npower League Two play-off places.
In a game of plenty of good, passing football there were few goalscoring opportunities until the last few minutes, and the U's defended well throughout the second period to hang onto their lead.
Wimbledon created the better openings early on, with Luke Moore's effort turned aside by keeper Ryan Clarke and Billy Knott driving just over from 20 yards.
Oli Johnson impressed for the hosts in the first half and he went close when, after getting behind the Dons' defence, his shot was blocked on the goalline by Pim Balkestein while Adam Chapman forced Brown into a decent save with a free-kick from 25 yards.
Johnson nearly made it two on 73 minutes with a strong header against the crossbar, although the home side's evening was soured late on when manager Chris Wilder was sent to the stands in stoppage time.
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