Dhoni's 76 not out spanned three hours and 22 minutes and saw him face 159 balls with 10 boundaries.
He received just enough support as India finished on 282 for nine, a wicket away from defeat, before bad light and rain halted play early on the final day to leave the teams all square heading into the second Test of this three-match series starting at Trent Bridge on Friday.
"I was really happy. I couldn't imagine this sort of innings," the 26-year-old Dhoni said after his fifth fifty in his 18th Test.
A more consistent performer with the bat in one-day cricket, where he averages just under 47 with an astonishing strike rate of nearly 99 percent, Dhoni added: "I've not played anything like that. My strike rate was 40 percent. This was a new achievement in my cricketing career.
"What has been talked about my batting up until now has been the aggressive game and playing this kind of game was very different for me."
India, set a stiff target of 380 to win, started the final day on 137 for three with Dhoni, who came in at No 7, contemplating the prospect of a pair after a first innings nought.
"I knew that if we lost a few wickets it would be a completely different scenario," Dhoni explained. "Instead of going for the game, we would have to save the game."
Dhoni monopolised the strike to such an extent that during a tenth-wicket partnership lasting 30 balls with Shanthakumaran Sreesanth, the fast bowler faced just seven deliveries.
Even though at that stage England captain Michael Vaughan was bowling his occasional off-spinners in tandem with spin specialist Monty Panesar so as to prevent the umpires making an offer of bad light to the batsmen, Dhoni said the final stand had been hard work.
"I was not really confident because the last wicket, it's a matter of just one ball. It was turning and Monty was bowling really well and there was rough for Michael Vaughan as well.
"It was quite tough but I decided if I could rotate the strike in the last two balls (of an over) I would do that but I was looking to play most of the balls."
His efforts didn't go unnoticed by India captain Rahul Dravid, one of several top-order batsmen out for a low score.
"His knock was really important," Dravid said. "The way he batted with the lower order was very crucial for us. He didn't score any runs in the first innings. Considering that, it was a very good effort."