James Constable put Chris Wilder's side in front with his seventh league goal of the season, but Rhys Murphy looked to have secured a point for the visitors.
Striker Kitson had the final say, though, ensuring Oxford were not held to a third consecutive league draw and remain a point better off than second-placed Chesterfield.
Paul Cook's Chesterfield were 2-0 winners over Plymouth Argyle courtesy of a Matty Brown header and a Marc Richards penalty.
Bottom-of-the-table Torquay ended Southend United's run of seven games without defeat thanks to John Marquis' second-half strike.
Fleetwood Town replace Phil Brown's side in third spot after Mark Roberts scored a late goal to clinch a 2-1 win at Lancashire rivals Rochdale.
Leon Johnson's stoppage-time strike ensured Wycombe Wanderers held high-flying Scunthorpe United to a 1-1 draw at Adams Park.
Burton Albion were unable to stretch their winning run to four League Two games ater being held to a 1-1 draw by York City, with Burton striker Billy Kee sparing Shane Cansdell-Sherriff's blushes after the defender had scored an own-goal.
Torquay's win ensured they are now level on points with Northampton Town, who drew 1-1 at fellow strugglers Bury.
