Reports earlier today revealed that the deal was nearing completion, with Peterborough believed to be keen to move the 27-year-old on after they had transfer-listed him for an alleged breach of club discipline.
Discussing his switch across East Anglia, Barnett has admitted that he is excited by the prospect of getting back to playing football on a regular basis.
"It's been a difficult week, with what's gone on so I'm looking at this as a new start and the chance to get back to playing football and enjoying my football as well," he said.
"I've not done that as much as I would have liked this season. Ipswich have given me a chance to come here and play some games and hopefully score some goals and that's what I'm looking to do.
"It's a fantastic football club. I have some good memories of the place after scoring here last season in one of my first games. Now I want to score goals for the club and I can't wait to get going."
Barnett, whose deal at Ipswich runs until January, joined Posh in February of this year from Crawley Town.