Kumiko Watanabe is a veteran Japanese voice actress born on October 7, 1965, in Chiba Prefecture. She is currently affiliated with the talent management firm Sigma Seven, having moved there from Arts Vision in February 2018. Her career in the industry began in 1985 after she trained at the Japan Narration Acting Institute. Her debut role was in the anime Musashi no Ken, and her first regular character role came in 1988 as Jun Yamano in Ronin Warriors.

Watanabe is highly regarded for her exceptional vocal range and versatility, allowing her to portray a wide spectrum of characters, from young boys and energetic teenagers to comedic figures and mature women. This skill is exemplified in the Bakusō Kyōdai Let's & Go!! series, where she voiced multiple characters, including J, Gouki Ichimonji, and others. A significant turning point in her career was her role as the antagonist Katejina Loos in the 1993 series Mobile Suit Victory Gundam, which broadened the range of female characters she was considered for.

The 2000s brought some of her most iconic and widely recognized roles. She voiced the mischievous fox cub Shippō in the long-running series Inuyasha and its sequel Yashahime: Princess Half-Demon. From 2002 to 2009, she played the Mother in the beloved comedy Atashin'chi, a role she later reprised. Perhaps her most famous role is the title character, Sergeant Keroro, in the hit comedy series Sgt. Frog (Keroro Gunsō), which she voiced from 2004 to 2011 and again in the 2014 revival. Director Junichi Sato specifically requested her for the part. Her other prominent roles from this era include Tomoki Himi in Digimon Frontier, J in the Bakusō Kyōdai Let's & Go!! franchise, Kyōko Shirafuji in the Wagnaria!! (Working!!) series, and Regina in Glitter Force Doki Doki (Dokidoki! Precure).

In addition to her animation work, Watanabe has a substantial presence in video games. She is the long-time voice of the titular character Klonoa in the Klonoa series, starting with the 1997 original. Her other game credits include Karol Capel in Tales of Vesperia and Yunobo in The Legend of Zelda: Breath of the Wild.

A notable recurring collaboration in her career is with director Yoshiyuki Tomino, having appeared in four of his works: Mobile Suit Gundam ZZ, Mobile Suit Victory Gundam, Brain Powerd, and Turn A Gundam. In 2012, she married fellow voice actor Kōji Tsujitani, whom she had worked with on Inuyasha. He passed away in 2018. A significant recent achievement in her career came in 2023, when she was selected to succeed Keiko Yamamoto as the voice of Hanako Hanazawa in the long-running and iconic national anime series Sazae-san.