The 25-year-old Czech, who had dropped to 164th in the world after an injury-plagued 12 months, was playing her first final since winning her lone grand slam at Wimbledon in 2023.
She was made to work hard for a 7-6 (12-10) 4-6 6-2 victory and even had to save six set points in the tight first-set tiebreak.
But her win represents perfect timing, coming a week before the start of Wimbledon where the 25-year-old will now again be a force to be reckoned with.
Wang, who had to battle through the qualifying process and then beat four top-20 players to reach her first-ever tour final, kept causing problems with her pinpoint accuracy as she fired repeated baseline winners.
The Czech's serve looked unbreakable until Wang earned her first break point in the seventh game, breaking Vondrousova who slipped and hurt her ankle on that point.
But the Czech came back to snatch the tie-break after the 23-year-old Wang had wasted six set points.
Wang showed few nerves in her maiden singles tour final and levelled after breaking her opponent once in the second set.
But Vondrousova, who beat Australian Open champion Madison Keys in the first round and world No.1 Aryna Sabalenka in the semi-finals in Berlin, raced back with two breaks of her own to go 4-1 up in the decider.
She then played a perfect service game at 5-2, with a superb dropshot, a crosscourt backhand winner and a powerful forehand that forced an error by Wang on match point number one, sealing her third career title.
In the Nottingham Open final, American McCartney Kessler lifted her third WTA Tour title, completing her perfect Wimbledon warm-up by beating Ukrainian Dayana Yastremska 6-4 6-4 in showery conditions in the English city.
The 25-year-old, who ousted top seed Beatriz Haddad Maia in the first round and also knocked out Britain's defending champ Katie Boulter, overcame two interruptions for rain, including a second delay for over an hour and a half, before triumphing.
Ukrainian Yastremska lost her second final of the year but knows there is a bigger picture, due to the ongoing conflict in her home country.
"It's been a tough week with what was going on in Ukraine so I have had to deal with a lot of things this week," she said.
"I want to say I am proud of myself, I am improving some things I am working on. Not the win, but I hope soon, it's day-by-day."
