The title looked to be heading to Manchester United until Edin Dzeko and Sergio Aguero both scored in injury-time to tilt the balance in the favour City.
QPR threatened a major shock when second half goals from Djibril Cisse and Jamie Mackie cancelled out Pablo Zabaleta’s opener.
With QPR reduced to ten men after Joey Barton’s sending off, City somehow scored twice in stoppage tome to secure their first top flight title since 1968.
Mancini believes they deserved to finish as champions and is tipping a big future for City.
“It was incredible – they deserved this,” Mancini told Sky Sports HD1. “To win it like this is incredible. I don’t think I’ve ever seen a finale like this.
“We didn’t deserve to lose, we had a lot of chances and we deserved to win the game and championship.
“It’s fantastic for the club and the supporters after 44 years. It’s been a crazy season and a crazy last minute.”
The Italian added: “Five minutes from the end, I didn’t think we’d win this game. But we deserved to win this and deserved to win the title. We were on top for 20 games.
“I think for us it was really important to start winning this championship, Manchester City can have a big future now.”