Chelsea beat West Brom to emerge champion of England
It looked as though Antonio Conte's side might be forced to delay the celebrations as they were frustrated for long periods by the resilience and organisation of the Baggies.
But the mood changed and the title was won with eight minutes left as substitute Batshuayi, who had previously endured a season of struggle after his £33m summer move from Marseille, ended a scrappy passage of play by steering a finish high past Ben Foster.
The final whistle sparked wild celebrations among Chelsea's fans as manager Conte was tossed high into the air by his squad.
The Italian can now set his sights on emulating compatriot Carlo Ancelotti's 2010 feat of winning the league and domestic Double as the Blues prepare for an FA Cup final against Arsenal at Wembley later in May.
Chelsea worthy champions
Chelsea's celebrations were fully deserved - the culmination of a superb season's work by Conte and his squad.
They had to work hard for victory against a West Brom side that demonstrated all the qualities that have made this such a satisfactory season for them but, as so often this season, Chelsea got the job done.
The Blues' main attacking threats struggled to find a spark, with Eden Hazard's frustration summed up with one long-range shot that went out for a corner, but Conte's side found a way to win, illustrating once again why they are worthy champions.
The losses at home to Liverpool and at Arsenal in September that hinted at early struggles seemed an age away as Chelsea's players were overcome with elation, as did the surprise defeat to struggling Crystal Palace at Stamford Bridge and the setback at Manchester United.
Chelsea, even when not at their best, proved themselves the strongest and most complete side in the Premier League - and they proved it again on a night when they were tested.