The top-seeded American, who defeated Belgian Olivier Rochus in last year's Newport, R.I., finale, fired 11 aces to defeat sixth-seeded countryman Ryan Harrison 7-6 (7-4), 6-3 at the International Tennis Hall of Fame.
He'll face wild card Hewitt after the Australian posted a 6-4, 5-7, 6-2 win over 2009 Newport Champion Rajeev Ram.
Hewitt made his first final in more than two years and will be looking for his 29th career title.
Before Saturday's matches, three-time Grand Slam champion and former world No. 1 Jennifer Capriati and three-time French Open winner Gustavo Kuerten were inducted into the tennis Hall of Fame.