Playing alongside England No. 3 Costas Papantoniou, and his son Lucas, Katz produced several top-class performances, winning nine man-of-the-match awards along the way.
Apollo hold an unassailable 19-point lead over Lowlands whom they meet in the cup final on April 3.
Katz said: “The Wembley and Harrow Table Tennis League is one of the strongest in England and to become champions with a match to play is a very proud moment for me.
“It’s been a true team effort and I’ve been lucky enough to play alongside my long-standing friend Costas, an England VETT international. My game has improved this season as a result of his input and at the moment, I feel I’m playing the best table tennis of my sporting career – which is reflected in my averages and man-of-the-match awards.”