The combative midfielder joins having spent two and a half seasons with the Dutch side, where he made 49 appearances after making the switch from his first club Al-Ahly.
The 24-year-old has won 19 international caps.
Commenting on the new signing, Sporting Director Damien Comolli said: "I have watched Hossam since he was 17 years old. He is a versatile, very physical and technically gifted midfielder who will offer us a number of playing options.
"He is a terrific addition to the squad."
We are delighted to announce the signing of Egyptian international Hossam Ghaly from Feyenoord on a four and a half year contract.