Halep began the week halting American 15-year-old Coco Gauff’s dream run and will end it at the Champions Ball after dismantling seven-times winner Williams 6-2 6-2 with an inspired display on Centre Court.
She is Romania’s first Wimbledon singles champion.
The 27-year-old set the tone by breaking the Williams serve in the opening game and raced into a 4-0 lead in front of 15,000 incredulous fans.
She remained rock solid throughout, making only three unforced errors in a remarkable display of defence mixed with clinical counter-punching. Williams simply could not respond.
Even when Williams fired herself up at the start of the second set and began thumping the ball with her customary power, seventh seed Halep refused to back off.
Halep weathered the squall, then reeled off the last five games of what she described as the match of her life.
Williams has now lost three Grand Slam finals without winning a set since returning to action last March, following the birth of daughter Olympia in September 2017.
But this was the most chastening as she lasted only 56 minutes before biffing a forehand into the net — her 26th unforced error — to end the contest.
It was the second shortest Wimbledon final since Martina Navratilova thrashed Andrea Jaeger in 1983, one minute longer than Petra Kvitova’s trouncing of Eugenie Bouchard five years ago.
Until Saturday the only other Romanian to reach a Wimbledon final was Ilie Nastase who finished runner-up in 1972 and 1976. Halep went one better as she added the Wimbledon crown to the French Open she won in 2018.