The deal is thought to be worth around £700,000 and the 23-year-old midfielder has been offered a two-year contract.
"I am enormously happy because it has always been my dream to play in the Premier League," he told iSport.cz.
The Czech's agent, Jiri Muller, said that he was surprised at the nature of the medical at Craven Cottage.
"It was very demanding," he noted. "I have never seen such a thorough medical as this. About 20 doctors and other experts checked Marcel."
Gecov made 62 appearances for Czech club Liberec, scoring twice.