The tourists came out to bat with less than an hour to respond, but bad light stopped play after only four balls - creating a puzzling anti-climax as match officials met.
Then the umpires came out to remove the bails - formalising the draw and signalling England's 2-1 series win after 16 years of waiting.
Plans for a victory parade from Lord's to Trafalgar Square tomorrow are already underway.
Earlier, Pietersen rode his luck to reach a triumphant 158 - his highest score in Test cricket, doing so after being dropped three times.
The South African-born batsman's Hampshire colleague Shane Warne maintained the nervous tension around the ground with four wickets - becoming the most successful bowler against England in history and extending his tally of victims to 38.
Beginning the day on 34 for one, a lead of 40 runs, England began serenely but collapsed before Pietersen led a recovery to 261 for seven with an unbeaten 131.
Only victory for Australia could extend their run of successful campaigns to nine and they were boosted in their chance when Glenn McGrath - passed fit for this contest after an elbow injury - removed captain Michael Vaughan and Ian Bell in as many balls.
Warne then increased the sweat for the home side and the majority of the 23,000 crowd by prising out Marcus Trescothick and Andrew Flintoff before lunch.
However, Pietersen opted to counter-attack in a bid to ease the pressure, hooking paceman Brett Lee into the stands at fine leg twice either side of bringing up a 70-ball half-century.
Having been put down twice at slip, the most straightforward of chances being put down by Warne off Lee when he had scored only 15, Pietersen's fortune extended to him being dropped for a third time in the innings, albeit from no more than a half-chance when another cross bat shot at Lee flew to Shaun Tait, who got a hand to the ball diving to his right but could not stop another boundary.
That over from Lee, the 43rd of the innings, cost 16 runs but the fast bowler continued to hurtle in and propel the ball down in excess of 90-miles-per-hour.
Paul Collingwood offered staunch support in a sixth-wicket stand, contributing only four to the first 50 runs, before being held at silly point by Ricky Ponting off Warne to encourage Australia that the chance of a run-chase remained.
That view was strengthened when rookie fast bowler Tait knocked over Geraint Jones' off-stump in his first over.
By then 25-year-old Pietersen was in sight of a maiden Test hundred, which arrived from 124 deliveries.
With three wickets intact at tea, England were almost at the finishing line of what has been a scintillating summer and the spectators revelled in the moment, alternating chants of 'there's only one Shane Warne' in appreciation of the great leg-spinner with calls of 'Warney's dropped the Ashes'.
Warne, 36 tomorrow, acknowledged the crowd in what will be his final Test appearance in this country but Pietersen refused to exit centre stage for long, pulling Lee for another six and then lofting Warne for another maximum.
England v Australia
The Brit Oval
England (2nd innings)
M E Trescothick lbw b Warne 33
M P Vaughan c Gilchrist b McGrath 45
I R Bell c Warne b McGrath 0
K P Pietersen not out 158
A Flintoff c & b Warne 8
P D Collingwood c Ponting b Warne 10
G O Jones b Tait 1
A F Giles not out 50
M J Hoggard not out 4
S J Harmison c Hayden b Warne 0
Total: all out for 335 (91.3 overs)
(England lead by 341)