Sayuri Yahagi is a Japanese voice actress born in Tokyo on September 22, 1986. She is affiliated with the talent agency I'm Enterprise and has been active in the industry since 2005. Yahagi spent part of her childhood in Hachinohe City, Aomori Prefecture. She decided to pursue a career in voice acting during junior high school, inspired by a friend who commented that her voice sounded like it belonged in anime. Her debut role was the lead character Karin Maaka in the 2005 television anime series Chibi Vampire, also known as Karin.

Throughout her career, Yahagi has portrayed a wide array of characters, demonstrating range from comedic and lighthearted roles to more serious and quiet personas. One of her earliest recurring roles was Izumi Segawa in the long-running series Hayate the Combat Butler, starting in 2007. She gained significant recognition for her work in several major franchises. She provided the voice for Haruna Sairenji in the To Love-Ru series, a role she has played across multiple seasons and original video animations since 2008. In the same year, she first voiced the character Ran-Mao in Black Butler, a role she would reprise in subsequent sequels and original video animations.

Yahagi is also well-known for her portrayal of the intelligent and sharp-tongued Suzu Hagimura in Seitokai Yakuindomo, a role that began in 2010 and continued through multiple television seasons, original video animations, and feature films. Her other notable leading and supporting roles from this period include Kaya Miyoshi in Bakuman, Mitsuhide Akechi in The Ambition of Oda Nobuna, and Kodama Himegami in Maken-Ki!.

In the 2010s, Yahagi continued to take on prominent roles in popular series. She voiced Michiru Hyodo in the Saekano franchise, which included two television seasons and a concluding film. She played Manami Okuda in the Assassination Classroom television series and its related film. In 2018, she took on the role of Maho Hiyajo in Steins;Gate 0. She has also voiced recurring characters in long-running franchises, such as Sakuya in Sword Art Online and its sequel War of Underworld, and Murasaki in the Senran Kagura anime and video game series. More recently, her roles have included Momoka Momozono in Super HxEros, Amane Katagiri in Senryu Girl, and Ganryu Sasaki in Shin Ikki Tousen.

Yahagi has been involved in several collaborative projects with other voice actors. She was a member of the voice acting unit Lala & Haruna with Haruka Tomatsu, formed in connection with the To Love-Ru series. She was also part of the unit TRIPLE BOOKING, which was related to the Seitokai Yakuindomo franchise. She has a long history of co-hosting radio programs with voice actress Ayane Sakura.

On January 31, 2015, Yahagi announced her marriage to a man outside of the entertainment industry via her agency's official website.