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.
Brown was later sent off and Reuben Reid failed to score the resulting spot-kick as Chesterfield secured their first win in three league games.
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.
There was no winning start for new Portsmouth manager Richie Barker as Newport County won 2-0 at Fratton Park courtesy of two goals in the space of three minutes from Adam Chapman and Michael Flynn.
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.
Bristol Rovers are hovering just a point above the relegation zone after a 2-1 defeat Morecambe.
Accrington Stanley were 3-0 down at home to Exeter City after only 24 minutes before making a fist of it to go down 3-2.
Elsewhere on Saturday, Hartlepool came back from two down to draw 2-2 at Cheltenham Town and AFC Wimbledon drew 0-0 at home to Mansfield.
