Czech striker Vydra, who has scored 20 times for the Hornets this season, beat 29-goal Crystal Palace forward Glenn Murray and Blackpool winger Tom Ince to the honour on Sunday night.
"He deserves it very much, he has done incredible things for us this year," Zola said.
"Since he came he showed some very good qualities, although at the beginning he did not have the experience.
"For a while he was on the bench but he never gave up, and as soon as he got the opportunity he took it and has not stopped scoring since.
"Not only is he a talented player on the pitch but he has shown me he is a very good character as well.
"The whole team has made a big contribution to the goals Matej has scored. But he also plays a big role in the build-up and in defence. I'm really pleased with the way he performs."