Hales made 53 from 40 balls and Harry Brook scored an unbeaten 42 as England defeated Pakistan by six wickets in Karachi in the first of the seven T20s.
It was England’s first match in the Asian country for 17 years.
Hales last played for England in 2019, the same year he was withdrawn from their preliminary 50-overs World Cup squad after the Guardian newspaper reported he was serving a three-week ban for recreational drug use.
“It was a very special feeling to be back on the park for England,” Hales said. “Three years felt like forever. To go out and score 50 on my return in a winning team is the stuff dreams are made of.
“It is a nice feeling. Guys said in the past it was never down to cricket, missing the three years, that was never in doubt.
“But there was always nerves and pressure coming back after three years having not played. It felt like a debut again, so it was a very special night.”
The second T20 will be played on Thursday.
England, who last toured Pakistan in 2005, are playing four matches in Karachi and three in Lahore before returning in December to play three tests in the second leg of the tour.
International teams have largely refused to tour Pakistan since an attack by Islamist militants on the Sri Lankan team bus in Lahore in 2009 killed six policemen and two civilians.