|This article is about a/an actor in Kamen Rider Zi-O.|
Watanabe was scouted when he was in college. He began his entertainment activities as a model and debuted as an actor in Kamen Rider Zi-O.
In 2018, he auditioned for the role of Sougo Tokiwa, but ultimately dropped out due him not resonating with the character. The producers later called him back to set and cast him in the role of Black Woz, and later White Woz.
In 2019, he starred as Naoto Watanabe in Taiwanese singer Jay Chou's music video for his song Won't Cry. 
Watanabe was a special guest for the July 11, 2020 livestream premiere of Kamen Rider Heisei Generations FOREVER in the United States. He gave words of encouragement for those struggling with the COVID-19 pandemic and gave away an autographed DX BeyonDriver.
- Keisuke Watanabe is the second actor after Erina Nakayama to have recurring dual roles in the same series, with one character of his portrayal being a Rider: White Woz and Mayu Inamori, and the other being a supporting character: Black Woz and Medusa (both Wozes later swapped their roles). Although unlike Nakayama who plays biological twins, both of Watanabe's roles are essentially two of the same person and also Riders at the same time.