Akiyama (12-1) is a highly decorated judoka and one of the biggest draws in Japan.
His accomplishments include winning the 2006 K-1 Hero's Grand Prix and a gold medal in Judo at the 2002 Asian Games.
"I'm excited to bring Akiyama into the UFC and I can see him making an immediate impact in the middleweight division," UFC president Dana White said in a statement. "Besides his great judo and submission game, he's a finisher, and UFC fans are going to love watching him because he always shows up to fight."
Akiyama had been fighting exclusively for K-1 and sister promotion DREAM since his debut at K-1 Dynamite!! on New Year's Eve 2004.
Akiyama's only loss on his record was his second career fight, a knockout loss to kickboxing veteran Jerome LeBanner.
Akiyama has also lost to Kazuo Misaki but the fight was changed to a no contest after officials determined Misaki's knockout knee was an illegal strike. Conversely, he's also had a win stripped away, against Japanese legend Kazuki Sakuraba, for applying lotion before his fight (he claimed it was for dry skin).
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