Humbert produced a sublime forehand passing shot to hold his serve in the opening game but was soon overpowered by Zverev, who forced a break in the third game.
A second consecutive break gave Zverev a 4-1 lead before he clinched the first set, making just four unforced errors to 17 from Humbert.
A double fault handed Zverev another break at the start of the second set and the German continued to grind Humbert down with his serve and punishing groundstrokes.
Humbert took just five points on return throughout and Zverev served out to claim his second Masters trophy of the season, after his Rome victory on clay in May.
That took the German past world number one Jannik Sinner for most victories this year (66) and he will next play at the ATP Finals in Turin from 10-17 November, when he will aim to win the season-ending showpiece for a third time.
In the doubles final, Briton Lloyd Glasspool and Adam Pavlasek were narrowly beaten by the sixth seeds Wesley Koolhof and Nikola Mektic.
The former world number one duo won 3-6 6-3 10-5 to claim their fifth title of the season and deny Glasspool and Czech Pavlasek, who were playing in their first tournament together.
