Bas Savage and a second-half double from substitute Nicky Forster gave the Seagulls their fifth win in eight games to leave them outside the play-off places only on goal difference.
Luton have now taken just one point away from Kenilworth Road in seven matches and to make the matters worse, they had full-back Alan Goodall sent off in the closing stages.
Brighton boss Dean Wilkins started with Savage upfront in place of the injured Alex Revell following his stoppage-time winner at Hartlepool.
He kept Forster and on-loan Ipswich midfielder George O'Callaghan on the bench, even though they are both back to full fitness and the decisions paid off handsomely.
Savage headed Brighton into a 40th minute lead from a Matt Richards' free-kick with his third goal in seven games.
He was left unmarked by a Luton defence which has managed only one clean sheet all season and they were caught out again in the 69th minute.
Forster, brought on just three minutes earlier in place of Dean Cox, capitalised on hesitancy by Chris Perry on the edge of his own penalty area to find the bottom corner with a precise left-foot finish.
Forster went into the match with only two goals in ten starts since his £75,000 summer move from Hull.
He doubled his tally after Luton briefly hinted at a revival by reducing the arrears in the 79th minute.
The impressive Darren Currie, returning to his former club, crossed to the far post where Calvin Andrew headed back for David Edwards to volley in from close range.
The Hatters' hopes of a comeback were extinguished in the space of a minute.
Goodall had already been booked when he clattered into Jake Robinson and received a second yellow card.
Luton were still trying to adjust when Forster met O'Callagham's cross with a soaring header into the roof of the net.