Pietersen smashed his ninth six straight back down the wicket to score the winning runs with five balls to spare, taking his tally to 103 and Delhi's to 162 for five, four clear of their target for victory.
The England batsman needed just 64 balls to bring up three figures, and his masterful innings covered for the failures of others as only Yogesh Nagar, unbeaten at the close on 23, and Ross Taylor (13) made it into double figures for the Daredevils.
They had run into early trouble when opener Naman Ojha went for just one and Virender Sehwag followed for seven, bringing Pietersen into the action sooner than he might have expected.
His partners continued to fall, with Mahela Jayawardene managing just six and Irfan Pathan five, but Pietersen stood firm, even if he rode his luck a few times.
The Chargers will be left to rue mistakes in the field as they had dropped him three times, when he was on 6, 68 and 94.
Bharat Chipli put him down at mid-wicket early on, a moment that could have altered Deccan's fortunes entirely, while JP Duminy and Kumar Sangakkara were guilty of later spills.
Pietersen's previous T20 best had been a 79 for England against Zimbabwe in 2007.
"This is absolutely amazing, this is what dreams are made of," Pietersen told ITV4. "You come here as an England player and it's very, very intimidating but to come here and have all these fans cheering for you is very special.
"That was my first Twenty20 100 so it will be pretty hard to beat."
Earlier, the Chargers had made 157 for eight, with Parthiv Patel making 45 and Shikhar Darwan 44, but Delhi had Shahbaz Nadeem (three for 16) and Morne Morkel (three for 23) to thank for keeping them in check.
The win sends Delhi above the Rajasthan Royals, having played a game less, while Deccan are stuck at the opposite end of the standings.
Delhi Daredevils: Naman Ojha (wk), Virender Sehwag (c), Kevin Pietersen, Mahela Jayawardene, Ross Taylor, Irfan Pathan, Yogesh Nagar, Ajit Agarkar, Morne Morkel, Umesh Yadav, Shahbaz Nadeem
Deccan Chargers: Shikhar Dhawan, Kumar Sangakkara (c & wk), Bharat Chipli, Tanmay Mishra, Dan Christian, JP Duminy, Abhishek Jhunjhunwala, Amit Mishra, Dale Steyn, Ankit Sharma, V Pratap Singh