Eighth-seeded Shelton, who knocked off defending champion Carlos Alcaraz in the quarter-finals, will play his first Grand Slam final on Sunday, when he'll be aiming to end American men's 23-year drought in the majors and deny French Open champion Zverev a second Grand Slam title of 2026.
He makes history as the first Black American man since Arthur Ashe (1972) to reach the US Open final and the first since MaliVai Washington to reach a Grand Slam final (Wimbledon - 1992).
"It's a lot of emotion," Shelton said in an on-court interview after a win that was watched by a star-studded New York crowd.
"My dad, my mom have sacrificed a lot for me to be in this position today. My dad lost his mom earlier this year, and she's the reason that he was able to play tennis.
"Without her, there's no Ben Shelton standing here today. So this one is for her. And I'm gonna need you guys on Sunday to to bring the energy. I'm going for it. I'm gonna leave it all on the court."
A pulsating all-American semi-final had seen both players vying to reach a Grand Slam final for the first time.
Shelton - who took down defending champion Carlos Alcaraz in the quarter-finals - will now have the chance to become the first American man to win a Grand Slam title since 2003, when Andy Roddick triumphed at the US Open.
Tiafoe got off to a bright start, claiming the first set after breaking when Shelton uncharacteristically double-faulted to trail at 5-4.
Tiafoe held to love to clinch the first set, but Shelton came flying out of the blocks to start the second.
An early break helped him into a 2-0 lead before Tiafoe responded with a break to level at 2-2.
Yet with Tiafoe's serve increasingly erratic, Shelton grabbed another break in the eighth game to go 5-3 up and then held to level.
The momentum was all with Shelton and Tiafoe had to fight off two break points before holding early in the third set.
However, Shelton - who had one serve initially clocked at 158mph before it was later adjusted to 144mph - made no mistake in the fifth game with a break to go 3-2 up.
Tiafoe needed to hold to keep the set alive in the ninth game, and a furious arm-wrestle saw the 11th seed once again save three break and set points.
Shelton though earned his fourth break point after pouncing on Tiafoe's second serve once more, scorching a backhand return down the line.
Shelton converted that when Tiafoe netted a forehand to find himself 2-1 down.
The fourth set went with serve until the 12th game, when Shelton grabbed the crucial break to seal victory.
