Hongō has appeared in several movies, including Moon Child, which also starred Gackt, Hyde and Leehom Wang. Hongō played the role of Sho as a child, while the adult role was played by Gackt. He appeared in a movie called Hinokio which was released in July 2005 in Japan. Hongō is also the young boy in the singer Yui's music video for her song "Tomorrow's Way." In 2006, Kanata was cast as the popular anime character Ryoma Echizen in the live-action adaptation film of The Prince of Tennis. He joined the majority of the Seigaku Regulars of the Prince of Tennis musicals as he was replacing Kotaro Yanagi, who couldn't play the role due to a car accident he was involved in.

Hongō also portrayed the young Bassist Shinichi Okazaki in the movie Nana 2, which was released in Japan on December 9, 2006. He had replaced Kenichi Matsuyama who had previously played Shin in the first Nana film. His next feature film was alongside Michael Pitt and Keira Knightley in Silk which was screened at the 2007 Cannes Film Festival. This marked Hongō's first appearance in an English language film, where he played a Japanese servant boy. He also starred in another music video, B'zs "Eien no Tsubasa" along with Tsubasa Honda and in GReeeeN's music video of "Namida Sora".

Hongō starred in three films in late 2008. They included Aoi Tori, K-20: The Fiend with Twenty Faces and Goth. The latter two were released in Japan on the same day, December 20. Goth is based on a Japanese novel with the same name, written by Otsuichi.

In 2011, he portray the role of Jōichiro Nishi in Gantz (live action movie) and Gantz Perfect Answer.

In October 2012, he starts his debut as anime voice actor in Btooom! as the lead character Ryōta Sakamoto.