In the avian battle between the Magpies and the Seagulls, the men in black and white were the dominant force throughout, but they wasted a plethora of chances and were hit with a Welbeck-sized sucker punch in the first half.
Coming into Saturday's game, Newcastle boss Eddie Howe had gone unbeaten in his first six Premier League home games against Brighton as a head coach - winning five of them - and that streak looked set to continue if the Magpies' early pressure was anything to go by.
Clinton Morrison on Sky Sports News could not recall a time where Brighton had played worse football, as Newcastle huffed and puffed relentlessly, but Howe's men were lacking that ruthless touch, in stark contrast to the in-form Welbeck.
The ex-Arsenal and Manchester United striker incredibly put Brighton ahead on one of the few occasions where they managed to get out of their own half in the first 45 minutes, and Newcastle fans would have been rightly bewildered at the half-time scoreline.
The story of the second half was almost identical to the first, with Howe's side unrelenting in their pressing and constantly banging on the Brighton back door, but Fabian Hurzeler's men were standing incredibly firm.
The Seagulls then suffered a major worry when Welbeck was carried off after taking a Fabian Schar knee to the back, but the visitors did their stricken teammate justice by clinging on for an extremely hard-fought win, one that takes them into the top five of the Premier League table as Newcastle - now winless in four - sit eighth.
NEWCASTLE VS. BRIGHTON HIGHLIGHTS
Danny Welbeck goal vs. Newcastle (35th min, Newcastle 0-1 Brighton)
Talk about being totally against the run of play! Brighton have had their backs against the wall for almost the whole of the first half, but they have just been given a lesson in ruthlessness by the rejuvenated Welbeck.
Lewis Dunk punts a free kick forward from inside their own half, and Welbeck chests it down before playing a neat one-two with Georginio Rutter and shrugging off two Newcastle shirts to slot home.
MAN OF THE MATCH - BART VERBRUGGEN
A deserved word for Welbeck, whom we can only hope has avoided a serious injury, but Bart Verbruggen was impenetrable in the Brighton goal, making six saves and two high claims to keep the Magpies at arm's length.
NEWCASTLE VS. BRIGHTON MATCH STATS
Possession: Newcastle 60%-40% Brighton
Shots: Newcastle 21-10 Brighton
Shots on target: Newcastle 6-5 Brighton
Corners: Newcastle 9-4 Brighton
Fouls: Newcastle 11-9 Brighton
BEST STAT
WHAT NEXT?
A daunting trip south is next on Newcastle's agenda, as the Magpies head to Stamford Bridge to battle Chelsea next Sunday afternoon, three days before hosting the Blues in the EFL Cup fourth round.
As for Brighton - who are anxiously awaiting updates on Welbeck's injury - Hurzeler's team welcome Wolverhampton Wanderers to the Amex on October 26 before hosting Liverpool in the last 16 of the EFL Cup four days later.