Dropped twice dropped by Makhaya Ntini in the outfield, he met fire with fire as South Africa's pace bowlers attempted to bounce him out, on Day 2 of the fourth Test.
Scorecard: England vs SA, 4th Test
He brought up the landmark with a trademark clip for four through mid-wicket, but two balls later was out for exactly 100 after fishing for a wide ball from Ntini.
South African-born Pietersen becomes only the third England captain to score a century in his first innings in the job after Archie MacLaren in 1897 and Allan Lamb in 1990.
Image: Pietersen celebrates his century as Makhaya Ntini looks on during day two of the 4th Test between England and South Africa at the Brit Oval on Friday in London. Photograph: Hamish Blair/Getty Images