His major breakthrough role was as Ryoma Echizen in the live-action film adaptation of The Prince of Tennis and became even more widely known when he was cast as Shin in Nana 2.

[2][3] Hongō has appeared in several movies, including Moon Child, which also starred Gackt, Hyde, and Leehom Wang.

In 2006, Hongō 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 could not play the role due to a car accident he was involved in.

He also appeared in the drama special Saigo no Bansan: Keiji Tono Kazuyuki to Shichinin no Yougisha, playing the character of a suspect among others.

In January 2012, Shirato Osamu no Jikenbo was aired at TBS, where Hongō played the role of Kurosaki Hitoshi opposite Yudai Chiba.

Hongō also appeared in the WOWOW series KAZEOKE in August 2013 and performed in the radio drama Inanagi in February of the same year.

He played the lead role in the film Tokyo Slaves, which was based on the Japanese novel series Doreiku written by Shinichi Okada.

Hongō also voiced Julian Ayers Mackenzie in the science fiction anime Gundam Build Fighters.

By 2014, Hongō was revealed to portray Armin in the 2015 live-action adaptation of the hit series Attack on Titan by Hajime Isayama, which was aired in August 2015.

Hongō starred in the 2016 drama-comedy film Yamikin Ushijima-kun Part 3 alongside Takayuki Yamada and Gou Ayano.

He also starred in the WOWOW series Kakko no Tamago wa Dare no Mono, and reprised his character as Makoto Naegi in Danganronpa: Kibō no Gakuen to Zetsubō no Kōkōsei THE STAGE 2016, which ran from June to July 2016.

He starred in the series Rabuho no Ueno-san based on the seinen manga of the same name, portraying the titular character Ueno, and he later reprised this role for its second season.

He also portrayed Seikyou in the live-action adaptation Kingdom based on the 2006 manga of the same name, and played the role of contract killer Kid in the film Diner directed by Mika Ninagawa.

He portrayed the character of Isami Kondō in the MBS drama Aozakura: Bōei Daigakukou Monogatari, which was based on the manga of the same name.

He also starred in the stage play MONSTER MATES, which ran from February to March 2019, and performed in the Reading·Stage Yubi to Bara on June 15, 2019.

He also portrayed Makoto Karaki, the protagonist of the adventure game Death Come True written and directed by Kazutaka Kodaka.