The 30-year-old began his career at FC Union Cheb before spending eight seasons at Slavia where he made over 170 appearances. He has also been capped three times by the Czech Republic, having previously made 11 appearances for their under-21 side.
"We have three very good young keepers - Marton Fulop, Robert Burch and Nicky Eyre - who are for the future," explained Sporting Director Frank Arnesen. "We need one for inbetween, with Kasey Keller gone, and we want to send the young keepers out for a loan spell at a higher level than reserve football.
"We were looking for a very good keeper, who has the ambition to play, but also knows Paul Robinson is in front of him. Cerny, who we know because of the relationship with Slavia Prague, is an international player for the Czech Republic behind Petr Cech.
"He is 31 in February and it is the ideal situation for him and us - and he will stay here for 18 months."
We are delighted to announce the signing of goalkeeper Radek Cerny from Slavia Prague. The Czech international has signed a 18-month contract.