[5] Iwata made his professional debut against Joel Bermudez on 8 December 2018, at the StubHub Center in Carson, California.
[6] He made his debut in the United States, as he was only given his domestic boxing license by the JBC on 31 January 2019, which allowed him to compete in Japan.
Although he had won nearly every round of the bout, Iwata appeared dissatisfied with his performance, stating "I wanted to hit the body a little more".
He won the fight by a fifth-round technical knockout, stopping Valladares with a flurry of punches at the 2:10 minute mark.
[12] Iwata was expected to face Rikito Shiba for the vacant Japanese light-flyweight title on 11 September 2021, at the Korakuen Hall in Tokyo, Japan.
[15] Iwata was booked to make his first Japanese light-flyweight title defense in a rematch with Toshimasa Ouchi.
Although Ouchi was able to rise from the canvas in time, he was unsteady on his feet, which prompted the referee to wave the bout off.
[22] On 3 September 2022, it was announced that Iwata would challenge the reigning WBO light flyweight champion Jonathan González.
Their fight was scheduled as the co-main event of the Kenshiro Teraji and Hiroto Kyoguchi light flyweight unification bout, which took place on 1 November 2022.