Sayaka Kobayashi is a Japanese actress and voice actress born on October 12, 1970, in Sapporo, Hokkaido. She graduated from Hokkaido Sapporo Minami High School and began her acting career in theater. On April 1, 1992, she became affiliated with the Seinenza Theater Company after completing training through the Institute of Literary Research and the Juvenile Research Institute. Her father was documentary film director Chigusa Kobayashi, and her mother was actress Nobuko Matsui, who performed in numerous television dramas.

Kobayashi has maintained an active career in voice acting since the 1990s. One of her early anime roles was Michelle in the 1999 series Wild Arms. In 2013, she took on the role of Taiko Namino in the long-running family anime Sazae-san, marking a significant recurring part in a major Japanese television institution. Her other anime credits include Suzana Tatekami in Fafner in the Azure: Exodus (2015), Lara's Mother in Garo: The Animation (2015), Nanami Sakuraba in Aikatsu Stars! (2016), and a role in Sword Art Online II.

Kobayashi is particularly recognized for her supporting roles in notable anime series. She voiced Yumiko Shindō in the 2015 mystery thriller series The Perfect Insider, known by its Japanese title Subete ga F ni Naru. She also voiced Akiko Makimura, the mother of Miki Makimura and wife of Noel, in the 2018 Netflix series Devilman Crybaby.

Beyond anime, Kobayashi has an extensive career in dubbing foreign films and television series into Japanese. She is the established Japanese dub voice for South Korean actress Son Ye-jin, American actresses Keri Russell and Tracie Thoms, and Vera Farmiga, whom she voices as Lorraine Warren in The Conjuring film series. Her extensive dubbing portfolio includes Japanese-language versions of films such as Brokeback Mountain, The Favourite, First Man, Notting Hill, and many others, as well as television series like Castle Rock, Sherlock, and Gossip Girl.

Kobayashi has also performed in live-action television and theater, appearing in dramas such as Kokoro and taking on roles in stage productions including Fiddler on the Roof, King Lear, and Plus Plastic. She has been noted for her versatility across stage, television, anime, and dubbing work.