Sakkari had lost six finals since winning her first title at the WTA 250 tournament in Rabat in 2019. She finished runner-up to Jessica Pegula in Guadalajara last year.
"We've heard so many bad things - that I will never win a title, that I'm a top-five player with only winning one title," said Sakkari, who broke down in tears after her win.
"That was very hard for me to overcome and I'm so happy that I did it here this week ... I want to thank my coach Tom who has been with me the last five years. We've waited for more than four years for a second title."
In Saturday's final, Dolehide rallied from a break down in a tight opening set to take a 5-4 lead, but Sakkari won the next three games to take the set.
She broke for a 3-2 lead in the second set and held for 5-3 with her third ace of the contest, before clinching victory after an hour and 43 minutes.
Sakkari, currently ranked ninth in the world, is expected to climb up to sixth when the rankings are updated on Monday, according to the WTA. Dolehide is set to break into the top 50 for the first time.
Sakkari, who has previously described Mexico as her second home, was presented with the champion's sombrero after her win and also wore the Mexican soccer team's shirt during the trophy ceremony.
"It's the biggest win of my career... I'm just very, very grateful that it happened here," she told a news conference later.
"I've said it many times this week, I just really enjoy my time here ... Tonight and tomorrow, it's going to be two very happy days for me."
Sakkari, currently ranked ninth in the world, is expected to climb up to sixth when the rankings are updated on Monday, according to the WTA. First-time WTA finalist Dolehide is set to break into the top 50 for the first time.
"I'm really proud of myself and I look forward to a lot more finals like this," Dolehide told reporters. "Hopefully next time it could go a little bit more towards my way. This is definitely something to build on."