In just his fifth England appearance the 23-year-old opener proved he was ready to fill the match-winning void left by Kevin Pietersen's retirement with the highest Twenty20 score by an England batsman.
"I was gutted to get out just short of 100 but at the same time we managed to get a win," said Hales, who was still dressed in his pads at the post-match press conference.
"But once it kicked in that I had got 99 in front of a home crowd I was thrilled. That's definitely been the highlight of my career so far. Without a shadow of doubt."
Hales mixed heavy hitting with some mature strokeplay as a 159-run stand with Ravi Bopara (59) for the second wicket ensured England reeled in a difficult-looking chase of 172 for four with two balls to spare.
While Hales was left disconsolate after falling just one run short of a deserved ton, when bowled by Ravi Rampaul in the penultimate over with four required for victory, the Nottinghamshire right-hander was left to reflect on a memorable day on his home ground.
The premature retirement of Pietersen - the world's top-ranked Twenty20 batsman when he called time on his limited overs career - has left England relying on a talented if young batting line-up ahead of their World Twenty20 title defence later this year.
And Hales, who at 6ft 5in has the same towering presence at the crease as Pietersen, admitted he had targeted securing Pietersen's place for the World Twenty20, saying: "Definitely so. I'm very pleased that the selectors backed me for this game.
"Hopefully I've shown them what I can do at this level and I'm very pleased I managed to cash in today."
England have just three more games scheduled, against South Africa in August, before they are due to fly out to Sri Lanka for their title defence a month later.
Stuart Broad's side boasted just two of the batsmen - Craig Kieswetter and Eoin Morgan - from the team that won the World Twenty20 final two years ago with Hales among four batsmen to have less than nine appearances to their name.