Bellator MMA will crown a new welterweight champion on April 18.
The card will air on Spike TV, with Lima-Hawn its main event.
Bellator is currently without a welterweight title-holder due to the departure of four-time defending champion Ben Askren. Bellator elected not to renew the contract of Askren (12-0), following his last fight in July.
"Without using too many clichés, Lima vs. Hawn is just a fight fans dream come true," Bellator CEO Bjorn Rebney said in a released statement. "Both are incredibly exciting to watch in the cage, and to have them set for a five-round battle for our welterweight title is something I couldn't be happier about."
Lima (25-5) cruised through the Season 8 welterweight tournament last year with three consecutive knockout wins. He came up short in a five-round decision loss to Askren for the Bellator title in April 2012.
Hawn (18-2) also navigated his way through a Bellator tournament in 2013, registering a victory in three consecutive months. A former U.S. Olympian in judo, Hawn fought Michael Chandler for the Bellator 155-pound title last January. He lost via second-round submission.
"It's great to be back in title contention and going for that belt," Hawn said. "In terms of size and skill, this will probably be the toughest fight of my career, and I'm ready for that."