Gillingham midfielder Payne signed a loan deal at London Road on Saturday and the 21-year-old will remain with the Championship strugglers for the rest of the season when the move could become permanent.
He admitted to having already spoken to Peterborough before Posh boss Darren Ferguson came calling again last week.
"I was impressed with what Darren had to say when I met him last summer," Payne told the club's official website. "I liked him a lot and it was 50/50 at the time whether or not I moved to Peterborough then.
"Things didn't work out then, but when I heard Peterborough were interested in me again last week I was very pleased.
"Gillingham has been my only club and I've been there 10 years so it was a wrench to leave them, but the time is right now for me to try and play at a higher level. But I'm happy to be at Peterborough and, to be honest, it was an easy decision to make."
Payne added: "I'm not looking too far ahead. I want to get in the team first team as I want to help the club avoid relegation, that's all I'm concentrating on for the moment."