Striker Leonardo Ulloa gave the Seagulls maximum points before a crowd of 27,700 at the Amex Stadium, with the only goal of the game coming midway through the second half.
Prospective owner Cellino was due to fly in from Miami at the start of an important week in which the Cagliari owner expects the Football League to approve his 75 per cent takeover of Leeds.
The 57-year-old Miami-based businessman, who was not believed to be at the game, remains in pole position in the race to buy a majority share in the Championship club.
Boss Brian McDermott and Cellino will meet for the first time since Cellino's botched attempt to sack him, with the Leeds chief increasingly determined to carve out a relationship with the Italian.
On the pitch, Brighton made a lively start and Spanish midfielder Andrea Orlandi put a free-kick over from the edge of the area early on after Solly March was tumbled over by Rodolph Austin.
Danny Pugh threatened for the first time for Leeds by firing wide following a run down the wing, before Brighton defender Inigo Calderon was cautioned for a late tackle on Austin.
Brighton's new Spanish striker David Rodriguez, making only his second start for the Seagulls, tried his luck from the edge of the area but failed to test keeper Paddy Kenny on 26 minutes.
Leeds defender Stephen Warnock was booked for going in late on March before Argentinian Ulloa put a first-time shot into the side netting after neatly chesting down a pass from Orlandi.
March should have done better when slicing the ball wide after Calderon and Orlandi combined cleverly for the Seagulls six minutes before the break.
Brighton keeper Tomasz Kuszczak saved comfortably three minutes after the break from midfielder Alex Mowatt's shot.
The Seagulls threatened at the other end when Rohan Ince drove forward and Calderon had a shot blocked from the edge of the box.
Brighton were struggling to find a spark in the final third of the field and head coach Oscar Garcia made his first change by introducing former Newcastle flyer Kazenga LuaLua in place of Rodriguez with 33 minutes remaining.
LuaLua quickly made his presence felt and after 64 minutes his cross found Ulloa, who fired past Kenny from 10 yards to score for the third time in three games against Leeds.
It was also Ulloa's second goal in successive games after his first in six matches defeated Doncaster last Saturday.
Leeds, who have now gone 10 games since keeping a clean sheet, attempted to hit back and Mowatt's low shot was saved by Kuszczak after a goalbound shot from March was kept out by Kenny.
United, who last lost away at Brighton eight years ago, never seriously threatened a late comeback as the Seagulls extended their unbeaten home run to seven games in all competitions.