Cech, who won four Premier League titles, the Champions League and four FA Cups for Chelsea, previously played for Guildford Phoenix and the Chelmsford Chieftains.
"It's clear Oxford have big ambitions and I hope I can help them with those," said Cech, who played the sport as a youngster before switching to soccer.
"Personally I'm looking forward to build on the experience with Chelmsford Chieftains... last season and help the team to reach new heights this coming season."