Saturday's 1-0 win at Colchester United coupled with MK Dons' home defeat to Walsall ensured the Posh will be playing in the Championship next season.
"I don't know why, but I had a feeling that we'd go up at Colchester. It's a wonderful day for everyone at the club and particularly the fans who've been awesome," said Ferguson.
"I'm a very lucky manager to be at this club with these players and this chairman. We've achieved two-thirds of our ambition and now we can plan the push for the Premier League."