The scores of the marathon match were 7-6 (14-12), 7-6 (7-5).
The victory made Zvonareva a four-time champion in her WTA career.
"When I won the (match) point, I didn't know the score," said a surprised Zvonareva, who titled for the first time in 17 months. "I thought I had to win one more point. But then the umpire said 'Game, set and match', and I was like 'I won' and it was great. After this win I've a lot of confidence now."
Zvonareva needed treatment for a nosebleed two times during the first set.
"After doing so well here I'm now looking forward to Wimbledon," said Jackson, who failed to win her first title. "I have more confidence going into it than if I hadn't done as well this week."