Officials close to the event confirmed the booking to ESPN.com. The bout will take place at a catchweight of 215 pounds and headline Bellator: Dynamite 2 inside Scottrade Center in St. Louis.
Jackson (36-11) hasn't fought in nearly a year because of a contract dispute with Bellator. Now 37, he made his debut with the promotion in November 2013 and made three appearances for Bellator in a six-month span, picking up wins over Joey Beltran, Christian M'Pumbu and Muhammed Lawal.
In late 2014, however, Jackson accused Bellator of being in breach of contract and announced he had re-signed with the UFC, where he fought from 2007 to 2013. Jackson claimed Bellator never provided him pay-per-view figures for his fight against Lawal in May 2014 and was contractually required to do so.
After signing Jackson, the UFC booked him to fight Fabio Maldonado at UFC 186 on April 25, 2015. One month before the event, Bellator filed suit against Jackson in New Jersey court, claiming Jackson was still under an exclusive six-fight contract.
Additionally, Bellator was granted a preliminary injunction aimed to prevent Jackson from fighting at UFC 186. That injunction was overturned on appeal, however, and Jackson was ultimately allowed to compete. He defeated Maldonado via unanimous decision.
A former UFC champion, Jackson publicly contemplated retirement before settling with Bellator earlier this year.
Ishii (14-5-1), 29, is an Olympic gold medalist in judo. He turned to mixed martial arts after winning gold at the 2008 Summer Games in Beijing. Fighting primarily in Japan, he has fought the likes of Fedor Emelianenko, Tim Sylvia and Mirko "Cro Cop" Filipovic. This will mark his Bellator debut.
Dynamite 2 is Bellator's second hybrid event, which features both professional MMA and kickboxing.