Atsushi Ohkubo was born on September 20, 1979, in Japan. As a young person, he was more drawn to drawing than to traditional academic studies, a passion that led him to pursue a career in manga. After completing his education at a specialized manga school, he became an assistant to Rando Ayamine, the artist of the series GetBackers, a role he held for two years.

Ohkubo began his professional manga career by winning a competition held by Square Enix's Monthly Shonen Gangan magazine. His first serialized work, B. Ichi, ran from 2001 to 2002 and was collected in four volumes. Following this, he created the series for which he first gained international recognition: Soul Eater. Serialized in Monthly Shonen Gangan from 2004 to 2013, Soul Eater became a worldwide success and was adapted into a popular anime television series by the studio Bones. Ohkubo later returned to this universe with Soul Eater Not!, a spin-off and prequel that was published in the same magazine from 2011 to 2014.

In 2015, Ohkubo began his next major work, Fire Force, which was serialized in Kodansha's Weekly Shonen Magazine. This marked a significant shift for the creator, as it was his first series to run in a weekly publication. Fire Force also received an anime adaptation. In May 2020, Ohkubo indicated that Fire Force would be his final manga series, which concluded in 2022. Beyond his own serialized works, he has contributed character designs for the video games Bravely Default and Bravely Second: End Layer, as well as artwork for the card game Lord of Vermilion. He also served as a character designer for the original anime series KamiErabi God.app in 2023.

Several recurring themes and a distinct artistic identity define Ohkubo's body of work. His art style is noted for its vibrant quality, excellent line work, and a blend of cartoonish character designs with elements of surrealism and dark fantasy. His narratives often feature supernatural or gothic concepts, such as shinigami (death gods) in Soul Eater and spontaneous human combustion in Fire Force. He has cited a range of diverse influences, including the director Tim Burton, filmmaker David Lynch, and manga artist Akira Toriyama's comedic series Dr. Slump. One of his notable creative decisions was to feature a female protagonist, Maka Albarn, in the shonen series Soul Eater, a choice made at a time when female leads in the genre were uncommon. He has also expressed a deliberate preference for keeping his series from becoming overly long, stating early in the creation of Soul Eater that he did not want the story to drag on for many years like some other popular franchises.

Atsushi Ohkubo's significance in the industry stems from creating two internationally successful manga properties, Soul Eater and Fire Force, both of which were adapted into major anime series. His work has been published by two of Japan's largest manga publishers, Square Enix and Kodansha. He has also served as a mentor to other manga artists; his former assistants include Kei Urana, creator of Gachiakuta, and Yoshiki Tonogai, creator of Doubt.