Playing in her first career semi-final, the 25-year-old Dolehide fought back from a break down in both sets against Kenin to win the all-American clash 7-5 6-3 in an hour and 25 minutes.
Dolehide, who saved four match points against Martina Trevisan in the quarter-finals, was 4-2 down in the opener before winning three straight games to take a 5-4 lead and taking the set.
She was trailing 3-1 in the second set and won five straight games for victory, saving five break points in the final game before sealing the result on her first match point.
"I'm really proud of myself for getting through that one today, because Sonya is not an easy player to get by," Dolehide, 25, said before Saturday's final, using Kenin's nickname.
"It feels amazing, and I'm so excited for tomorrow."
World No.9 Sakkari reached the Guadalajara final for the second straight year after a 6-3 6-0 win over third seed Caroline Garcia of France.
Sakkari, who lost to Jessica Pegula in last year's final, has not dropped a set this week and is aiming to win her first title since the WTA 250 tournament in Rabat in 2019.
The 28-year-old has endured a disappointing grand slam year as she followed a third-round appearance at the Australian Open with first-round exits at the French Open, Wimbledon and the US Open.
"I said it the first day that I felt like this was the week, this is the place where I was going to overcome a lot of difficult obstacles and difficult emotions," Sakkari said.
"I don't want to go back to the US Open because that's passed, but I'm just so happy to be back in the final and to get to stay until the end of the tournament. I couldn't have asked for anything better this year."
