The ex-United striker opened the scoring at the AMEX Stadium with a clinical finish, capitalising on Kaoru Mitoma’s cut-back to notch his 100th club career goal.
This landmark achievement also highlights Welbeck’s remarkable consistency, as he has now scored in each of the last 15 Premier League seasons.
Welbeck, who left United in 2014 to join Arsenal, has scored against his former club more than any other ex-Red Devil.
His goal on Saturday added to his tally of 29 goals in 142 appearances for United, alongside his subsequent stints at Arsenal, Sunderland, Watford, Preston, and now Brighton.
Manchester United, coming off a narrow victory over Fulham on matchday one, looked to build momentum but found themselves frustrated in a tightly contested match.
Erik ten Hag’s unchanged lineup from the previous game showed promise early on, with United dominating possession and pressing high up the pitch. However, despite their efforts, they struggled to break down a resilient Brighton defence.
The match took a decisive turn in the 31st minute when Welbeck pounced on a loose ball in the box to give Brighton the lead.
United responded by pushing forward, with Marcus Rashford coming close to equalising, only for his goal to be ruled offside. However, Amad Diallo grabbed the equaliser for Man United on the hour-mark as the visitors looked posed to go on and win the game.
As the match wore on, though, United’s frustration grew, compounded by a VAR decision that disallowed Alejandro Garnacho’s goal due to offside.
Brighton, meanwhile, remained composed and capitalised on their chances.
In the dying moments of the game, Joao Pedro headed home a cross following a corner to secure a 2-1 victory for the Seagulls, handing Manchester United their first league defeat of the season.
Erik ten Hag now faces questions about his tactical decisions and team selection, as United’s inconsistent form continues to raise concerns.
Brighton, buoyed by their victory, will next face Crawley Town in the EFL Cup before a challenging league encounter with Arsenal at the Emirates.