But his 113 fails to remove Australia's grip on the third Test, with England closing 34 runs short of avoiding the follow-on at Old Trafford.
Kevin Pietersen's Ashes ton shows he is still man for big occasion
Pietersen dug his team out of a hole by hitting 113 - his 23rd career Test hundred - but was one of three batsmen dismissed after tea by Australia, which reduced England to 294 for seven in reply to 527 for seven declared.
If the English lower order, starting with Matt Prior (6) and Stuart Broad (9), can get the team past the follow-on mark of 328, Australia's hopes of victory to keep the series alive would be seriously dented with only two days left.
It means the opening hour's play today could define the five-match series, with England 2-0 ahead and only requiring a draw to retain the Ashes urn.
Weather could also be a factor, with some rain forecast on both days.
"We've gone OK," said Pietersen, who became England's leading run-scorer in all formats with 13,194, overtaking Graham Gooch.
"We can get the runs to avoid the follow on and even if we don't, then we can bat for a good length of time."
Ian Bell continued his fine form this summer by scoring 60 in a crucial 115-run stand for the fifth wicket with Pietersen, and Alastair Cook added 26 to his overnight tally to make 62, but the day was all about Pietersen.
The South African-born batsman was only playing here after passing a fitness test on a left calf injury sustained in England's victory at Lord's two weeks ago.
There was a train of thought that he should be rested and kept fresh for the final two Tests of the series - the selectors will be thankful they kept faith with their superstar batsman now.
Few batsmen have the ability to take a game away from an opposition like Pietersen can. That is why the England & Wales Cricket Board went to such great lengths to bring him back into the fold after the damaging and drawn-out phone-message row that marred last year's Test series against South Africa.
He came to the crease with England stumbling to 64 for three, following Jonathan Trott's dismissal for five, and made a jittery start, wafting at a couple of wide balls and nearly getting bowled. Once he got settled, though, it was a masterclass.
"I like performing on the big stage, when the team needs you," Pietersen said. "I like to stand up and be counted.
"If you play for England or Australia, your career is defined on how you perform in Ashes cricket."
Assuming the lead role after captain Cook fell caught behind to a legside delivery by Ryan Harris, Pietersen joined forces with Bell in what could prove to be a series-clinching partnership.
Despite the precarious situation, Pietersen did not hold back on a good batting track, signalling his intent by lofting Nathan Lyon over mid-off for an early four and then smashing the off-spinner for two sixes in a row to bring up his fifty off 71 balls.
Bell was seeking a century in a fourth successive Ashes Test and also sent Lyon over the ropes, which was enough for Australia captain Michael Clarke to remove him from the attack.
Australia was becoming demoralised, Shane Watson even more so when he rapped Pietersen on the pad but did not go for a review.
Replays showed the ball would have hit leg stump and Clarke buried his head in his hands after seeing the big screen.
Wicketless in the second session, the Australians finally found some joy when Harris clean-bowled Bell, but Pietersen soldiered on and brought up his century with a typically flamboyant uppercut for four off Mitchell Starc over point. He removed his helmet and flourished his bat to the crowd, to huge applause.
Pietersen was still around, but specialist batsmen ran out at the other end when Jonny Bairstow, who never looked secure, edged a rejuvenated Starc to Watson at second slip for 22.
Pietersen only made five scoring strokes in 41 deliveries after reaching three figures and his 206-ball innings ended when he was trapped lbw by Starc, although a review was needed to confirm his departure, made to a standing ovation.
"To make sure he didn't stay in and get a big one was key," said Starc, the pick of the bowlers with figures of three for 75, before adding cheekily: "It's always nice to get a big scalp - and it's always nice to get Kevin out as well."
Prior and Broad dug in grittily in the final half-hour, with six of the last seven overs being maidens. Australia will not be giving up without a fight.
"It's going to be a big half-hour," Starc said. "We need to take these three wickets as quickly as we can."
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