French Open runner-up Zverev, the world number four, came through 6-7(5), 6-3, 6-4 against his French opponent.
Zverev, a two-time finalist at Halle, becomes the first man since Roger Federer (2012-2019) to reach back-to-back semi-finals at the key Wimbledon warm-up tournament.
"After the French Open, I was hoping on grass I would play a bit quicker and not play for two-and-a-half, three hours every single match, but I’m continuing what I always do," said Zverev.
Zverev will take on 2022 champion Hubert Hurkacz for a place in the final.
Poland's world number nine defeated Marcos Giron of the United States 7-6(5), 6-4 on the back of 42 winners, including 11 aces.