Shinichirō Watanabe was born in Kyoto, Japan, on May 24, 1965. He began his career in the anime industry by joining the studio Sunrise, where he worked on episode direction and storyboards for various productions. His directorial debut came in 1994 as the co-director of the mecha series Macross Plus. He is widely recognized as an auteur of Japanese animation, known for directing critically acclaimed and commercially successful series.

Watanabe's career is defined by a focus on original creations rather than adaptations. His first full solo directorial venture was the 1998 series Cowboy Bebop, a space western that blended film noir, Hong Kong action cinema, and jazz music. The series received universal praise and was followed by the theatrical film Cowboy Bebop: Knockin' on Heaven's Door in 2001. In 2004, he directed Samurai Champloo, which merged a historical Edo-period setting with an anachronistic hip-hop soundtrack. His other notable original television works include the coming-of-age jazz drama Kids on the Slope (2012), the surreal space comedy Space Dandy (2014, as chief director), the thriller Terror in Resonance (2014), and the music-centric series Carole & Tuesday (2019, as chief director). After a six-year gap, he returned to directing with the science-fiction action series Lazarus in 2025, produced by Studio MAPPA for Adult Swim.

While best known for original works, Watanabe has occasionally participated in adaptations and anthology projects. He directed two short films, Kid's Story and A Detective Story, for the American-produced anthology The Animatrix in 2003. He also directed the anime short Blade Runner Black Out 2022 in 2017 and served as creative producer on the subsequent series Blade Runner: Black Lotus. He received an associate producer credit on the live-action Netflix adaptation of Cowboy Bebop but was not involved in its production and publicly criticized it after its release. He has expressed a desire to adapt the works of science-fiction author Philip K. Dick should the opportunity arise.

A defining characteristic of Watanabe's artistic identity is the prominent role of music in his storytelling. He views music not merely as background support but as an equal partner to the visuals, often aiming for a fifty-fifty relationship between the soundtrack and the narrative. His series are frequently noted for their eclectic and carefully curated soundtracks, most often composed by Yoko Kanno, which range from jazz and blues on Cowboy Bebop to hip-hop on Samurai Champloo and post-rock on Terror in Resonance. He is a self-described music fanatic, and his work on Carole & Tuesday was explicitly built around the bonds created by music. His characters often hide deep-seated loneliness and past trauma beneath a veneer of cool style, a theme he believes has remained relevant over time. He deliberately strives to make each of his projects feel different from the last and has expressed interest in directing a horror series in the future.

Watanabe holds significant importance in the anime industry, frequently ranking among Japan's best animation directors. He is considered a gateway creator for many international fans, in part because his work draws heavily on global cultures and American pop music and cinema, which he credits to a childhood desire to escape his rural surroundings. He prioritizes creating original anime over adaptations, believing it to be more worthwhile, and has noted that audiences have grown more conservative, preferring known intellectual properties. His influence and reputation allow him to collaborate with a wide range of international talent; for Lazarus, he worked with John Wick director Chad Stahelski on action choreography and musicians such as Kamasi Washington, Bonobo, and Floating Points for the score. He maintains a philosophy of creating cutting-edge work that can survive beyond its own era, inspired by a quote from musician Miles Davis.