Benda (23) has started six Championship matches for the Swans including the first five matches of the current campaign when he kept clean sheets at at home to Sheffield United and at Bristol City. He also kept a clean sheet in a 3-0 Carabao Cup win at Reading.
Benda hasn’t played in the Swansea first-team since a 2-0 defeat at Brighton in the Carabao Cup on September 22.
Benda moved to Swansea from German club 1860 Munich in 2017. He played 24 games on loan at Swindon Town in League Two in the 2019-20 season.
Benda, who is 6ft 4ins tall, will put immediate pressure on current number one Dai Cornell with teenage Posh ‘keeper Will Blackmore expected to leave on loan to gain first-team experience.
Posh boss Darren Ferguson said: “It’s a good signing for us. He’s a good size, a good goalkeeper and he’s very decent with the ball at his feet which is important these days.
“We needed competition for Dai and we need to get Will out on loan.”
Benda signed a fresh three-year contract at Swansea in January, 2021.