Watanabe was born in Kyoto. After joining the Japanese animation studio Sunrise, he supervised the episode direction and storyboards of numerous Sunrise anime, and soon made his directorial debut as co-director of the well-received "Macross" update, "Macross Plus". His next effort, and first full directorial venture, was the 1998 series "Cowboy Bebop", which received universal praise and is considered by many to be one of the greatest anime series of all time. It was followed by the 2001 film "". In 2003, Watanabe directed his first American-produced anime, the short films "Kid's Story" and "A Detective Story", both part of The Wachowskis' "The Animatrix", an anthology of animated short stories from "The Matrix". His next directorial effort was the critically acclaimed 2004 anime series "Samurai Champloo" which began broadcasting on Fuji Television in Japan on May 19, 2004.