Kentarō Mashiro is a Japanese voice actor born on July 12, 2001, in Osaka Prefecture. He is affiliated with the talent agency Stay Luck.

Mashiro's career in voice acting began in 2020. His debut role was as Kotetsu in the short-form anime series Mitchiri Wanko! Anima~tion, which premiered in April of that year. Kotetsu is characterized as a dog who initially has little to say but cannot stop talking once he starts.

A significant early milestone in his career came when he was selected through a public audition, held by the agency Horipro, for the lead role in the original anime Muteking the Dancing Hero. He voiced the protagonist, Muteki, in this 2021 series.

In 2022, Mashiro took on the role of Tsubasa Namioka in the soccer anime Shoot! Goal to the Future. That same year, he was part of the cast for the web anime Tomica Heroes Jobraver: Tokusō Gattai Robo, providing the voices for multiple characters, including Jobroid RAY and Police Braver ZERO.

Throughout the early 2020s, Mashiro has continued to build his resume with supporting roles in various television and web anime series. These include appearances in Reborn to Master the Blade, The Gene of AI, The Foolish Angel Dances with the Devil, and The Wrong Way to Use Healing Magic in 2023 and 2024. He has also taken on roles in the second season of The Great Jahy Will Not Be Defeated! and in the 2025 series The Water Magician.

Mashiro's professional affiliations have changed over time. He initially joined Horipro in March 2020. He left that agency at the end of 2023 and became a freelancer before joining his current agency, Stay Luck, in February 2024.