One Ok Rock (Japanese: ワンオクロック, Hepburn: Wan Oku Rokku, stylized in all caps) is a Japanese rock band formed in 2005. The band currently consists of vocalist Takahiro Moriuchi, guitarist Toru Yamashita, bassist Ryota Kohama, and drummer Tomoya Kanki. Former members include drummer Yu Koyanagi and guitarist Alexander "Alex" Reimon Onizawa. They play varied styles of music, with songs ranging from alternative rock and emo to post-hardcore and pop punk.

One Ok Rock was affiliated originally with Amuse. ever since their debut in 2007. The band left Amuse on April 1, 2021, and established their own management agency, named 10969 Inc. In the United States, they are signed with record label Fueled by Ramen.

One Ok Rock rose to international fame with their 2012 single "The Beginning" from their sixth album Jinsei×Boku=, which led them to concerts and music festivals outside Asia. Following the success, the band started to release their later albums in two versions (Japanese-English and full English) with 2 to 3 different tracks in each version. Their seventh studio album, 35xxxv, became their first album which charted on US Billboard. It peaked at No. 11 on Heatseekers Albums, No. 43 on Independent Albums, No. 23 on the Hard Rock Albums, and No. 1 on the World Albums Chart. The band's eighth album, Ambitions, debuted at No. 106 on the US Billboard 200 and international charts while incorporating more arena rock and pop-rock. In 2019, the band adopted a more electronic and pop sound on their ninth album Eye of the Storm. In 2022, they experimented with more rock-centered sound while still incorporating modern pop-rock for their new album, Luxury Disease.

One Ok Rock won Classic Rock Roll of Honour Awards for Eastern Breakthrough Male Band in 2016, and Rock Sound Awards for Best International Band in 2017 and Best Live Performance in 2018. The band was also nominated for two Alternative Press Music Awards – Best International Band in 2016 and Best Breakthrough Band in 2017.