The second-seeded Bertens came back from 5-2 down in the first set to win four straight games and force a tiebreaker. Vekic, the eighth seed, saved three match points in the second set before Bertens closed out the match for her eighth career title.
The win continued Bertens' emergence as a more versatile player. Until she beat Simona Halep to win the Cincinnati Open in August, Bertens had never reached a WTA final on any surface other than clay, but she has now won three straight hard-court finals.
Bertens' current ranking of eighth is the best for a Dutch woman since Betty Stove, who reached No. 5 in 1977.