The top-seeded Wawrinka clinched by breaking serve with a fierce forehand crosscourt pass to beat left-hander Zverev's advance to the net.
Wawrinka's first title in 2017 is the 16th of his career, and the seventh on clay including the 2015 French Open.
The Swiss is the No. 3 seed at Roland Garros, and first plays the 152nd-ranked Josef Kovalik of Slovakia.
Zverev, who came through qualifying, still seeks a first career title at age 29. The Russia-born German's second runner-up finish comes more than six years after his first, at Metz, France.