The 18-year-old has signed from Premier League champions Manchester City.
Susoho, who has already made his City debut, was on their preseason tour of the United States.
"I want to get out of my comfort zone and I feel this loan move will allow me to do that," he told the Peterborough website.
"I would describe myself as good in possession, calm and someone who can help the defense and the attack.
“I really enjoyed the tour in America with City and now I am looking forward to this loan move."
"It was tied up a while ago, but we were just waiting on Manchester City in terms of the dates," said Peterborough boss Darren Ferguson.
"I think he is a big signing for us. He is going to add to our options in the middle of the pitch - we felt we needed a bit more depth in there."