Masaaki Yuasa was born on March 16, 1965, in Fukuoka, Japan. After graduating from the Department of Fine Arts at Kyushu Sangyo University, he began his career in 1987 at the animation studio Ajia-do Animation Works, where he studied under Tsutomu Shibayama. He later worked as a freelance animator before rising to prominence as a director and screenwriter. In 2013, he co-founded the animation studio Science SARU with producer Eunyoung Choi, though he stepped down as its president in 2020.

Yuasa made his directorial debut with the feature film Mind Game in 2004, which won numerous awards including the Grand Prize at the Japan Media Arts Festival. He is also credited as the director of the 2019 animated film Ride Your Wave, which features a screenplay by Reiko Yoshida. The film won the Best Animated Feature Film award at the Shanghai International Film Festival and the Sitges International Fantastic Film Festival of Catalonia.

Throughout his career, Yuasa has directed a significant number of original works as well as adaptations. His notable original projects include the television series Kemonozume (2006), Kaiba (2008), and the short film Kick-Heart (2013), which was notably crowdfunded. He directed the original feature films Lu Over the Wall (2017) and Night Is Short, Walk On Girl (2017), the latter of which won the Japan Academy Prize for Animation of the Year. His later original film, Inu-Oh (2021), was selected for the Venice Film Festival.

In addition to his original creations, Yuasa has directed acclaimed adaptations. These include Ping Pong the Animation (2014), an adaptation of Taiyo Matsumoto's manga; Devilman Crybaby (2018), based on Go Nagai's classic manga; and Japan Sinks 2020 (2020), based on the novel by Sakyō Komatsu. He also directed an episode of the American animated series Adventure Time titled Food Chain (2014).

Yuasa's artistic identity is characterized by a visually adventurous and often surreal style. His works are known for their frenetic energy, fluid movement, and a tendency to shift art styles within a single piece. His films and series frequently explore themes of youth, identity, friendship, and the nature of creativity. For example, his film Inu-Oh blends modern rock music with 14th-century Japanese history, while his series Keep Your Hands Off Eizouken! (2020) serves as a vibrant celebration of the animation-making process.

Yuasa is widely regarded as one of the most significant and innovative directors in contemporary animation. His works have received critical acclaim and major international awards, including the Cristal for Best Feature Film at the Annecy International Animated Film Festival for Lu Over the Wall and the Grand Prize at the Ottawa International Animation Festival for Night Is Short, Walk On Girl. In 2021, he was honored by the Japanese government with the Medal of Honor with Purple Ribbon for his contributions to the arts.