It was Kerber's third title at the majors to add to her Australian Open and US Open triumphs in 2016.
Serena, 36, had been attempting to win a first Grand Slam since giving birth to her daughter Olympia in September.
Meanwhile, Novak Djokovic is one match away from a first Grand Slam title since 2016 after an epic five-set win over Rafael Nadal in their delayed Wimbledon semi-final.
Djokovic, who won 6-4 3-6 7-6 (11-9) 3-6 10-8 in five hours and 16 minutes, will face Kevin Anderson tomorrow.
The Serb led by two sets to one when play stopped yesterday.
Spain's Nadal broke twice in the fourth set when it resumed today, but Djokovic fought back to take his second match point to edge a dramatic decider.
This was Nadal and Djokovic's 52nd meeting - more than any other two men in the Open era - and the pair did not disappoint as they finally resumed their long-standing rivalry on the Grand Slam stage.
With 29 major titles between them, two of the game's all-time greats had not faced each other this deep in a major since the 2014 French Open final.