In a match that lasted 1 hour and 16 minutes, Isner battled his way through the first set, just before breaking his opponent at the beginning of the second. He then went on to hold his serve to give himself a chance to defend his title from last year, when he beat Belgian Olivier Rochus in the final.
Lleyton Hewitt became his final contender after defeating American Rajeev Ram in the other semifinal, prevailing in three sets 6-4 5-7 6-2 in 2 hours and 21 minutes.
Ram, who managed to win this tournament three years ago, put up a great fight before succumbing to Hewitt in the deciding set.
It will be the first final appearance for the former world no.1 Australian since winning the Halle title in 2010, beating the 17 time Grand Slam Champion Federer in the final.
He also reached 7 grass court finals in his career, winning all of them, with the highlight being Wimbledon 2002, when he conquered Argentine David Nalbandian to take the crown.
“I’ve never beaten him before and I’ve never played him on grass. It’s going to be a big challenge. It’s also going to be an honour sharing the court with him. He’s one of the guys I really, really respect.” said Isner when asked about the final encounter against Hewitt.