Wozniacki was looking to gain some momentum ahead of next week's championships at SW19, but she floundered on the windswept south coast in Friday's semi-final, losing 6-7 (8/10) 7-5 6-3 to her American opponent.
The former world number one and Hampton both played erratically in the first set before the Dane came from behind to edge a tie-break.
A total of 11 breaks of serve took place over the first two sets but Hampton did enough to take the second after a pep talk from her coach.
Wozniacki, clearly annoyed at the number of unforced errors she was making, beckoned her coach down from the stands for a chat halfway through the decider, but she failed to regain her composure and Hampton progressed to the final after breaking in the eighth game.
Hampton will now play her first WTA final against Elena Vesnina tomorrow after she beat Belgian Yanina Wickmayer 6-2 6-0 in Friday's other semi-final.
Wozniacki is seeded ninth for Wimbledon but she has not won a WTA title since last October and is now a big outsider for the tournament.
Hampton said afterwards: "It feels great. This is what we play for, to challenge for titles.
"I was winning in the first set tie-break so it was tough to lose that one.
"I was serving terribly and it was really windy, but I regrouped mentally."