Ken Ono (born March 20, 1968) is an American mathematician with fields of study in number theory.

[2] He is the son of mathematician Takashi Ono, who emigrated from Japan to the United States after World War II.

[8] In a joint work with Jan Bruinier, Ono discovered a finite algebraic formula for computing partition numbers.

[9] In 2014, a joint paper by Michael J. Griffin, Ono, and S. Ole Warnaar provided a framework for the Rogers–Ramanujan identities and their arithmetic properties, solving a long-standing mystery stemming from the work of Ramanujan.

[11] In a 2015 joint paper co-authored with John Duncan and Michael Griffin, Ono helped prove the umbral moonshine conjecture.

[12] In May 2019, Ono published a joint paper (co-authored with Don Zagier and two former students) in the Proceedings of the National Academy of Sciences on the Riemann Hypothesis.

[15][16][17][18][19][20][21] Ono wrote, with Amir Aczel as coauthor, an autobiography, emphasizing the inspiration he gained from Ramanujan's mathematical research.

[22][23] Ono was an Associate Producer and the mathematical consultant for the movie The Man Who Knew Infinity, which starred Jeremy Irons and Dev Patel, based on Ramanujan's biography written by Robert Kanigel.