They moved above Oldham with a well-deserved victory which stretched their unbeaten home run to six games. Glenn Murray was the hero again following his £300,000 move south from Rochdale during the January transfer window.
He scored his fourth goal in five starts in the second half to stretch Oldham's miserable recent away run.
They have now failed to win in five matches on the road and have scored only one goal over that barren period - from the penalty spot.
Brighton could have been well in command inside the opening 20 minutes, Murray's partner Nicky Forster spurning two chances to end a drought dating back to mid-December.
The Brighton captain was denied by Latics goalkeeper Mark Crossley when a pass by former Ipswich team-mate Dean Bowditch put him through early on.
Forster also headed high and wide from a Dean Cox cross and defender Andrew Whing went close with headers from two Cox corners.
Oldham posed little threat and they suffered a blow midway through the first half when top scorer Craig Davies was hurt as he fired over and had to be substituted.
Murray delivered the decisive blow in the 61st minute. Left-back Matt Richards, on loan from Ipswich, made a surging run through the middle before releasing him and the in-form striker rounded Crossley to find the empty net from a tricky angle.
Centre-half Tommy Elphick made certain of the points for Brighton 11 minutes later with a saving tackle to foil Deane Smalley, Davies' replacement, when the substitute looked favourite to convert a low cross by Lewis Alessandra.