Newcastle moved up to fourth in the Sky Bet Championship with a 2-0 victory that brought an end to Brighton's six-month unbeaten run.
The Seagulls had not lost in the league, excluding May's play-offs, since February but could not prevent the Magpies from making it three wins in a row to help forget about starting the campaign with two defeats.
Newcastle captain Jamaal Lascelles put Rafael Benitez's side in front after quarter of an hour with a powerful header before Jonjo Shelvey added the crucial second in the 64th minute with a sublime free-kick.
Brighton, whose manager Chris Hughton led Newcastle to promotion in 2010, could find no way back after that having been reduced to 10 men when Sam Baldock was sent off for a second caution in the 55th minute.