Sean Kennard was born in San Diego, California to an American father and Japanese mother. He grew up in Hawaii and his family moved to Philadelphia when he began studying at the Curtis Institute of Music, at age 13.
Kennard began lessons at the Ellen Masaki School of Music on his tenth birthday, 3 October 1994 in Honolulu, Hawaii, and began studies with Ellen Masaki on 5 January 1995. In the summer of that year he gave his first public solo performance in Honolulu. He performed in Carnegie Hall on 18 May 1996 as part of the Hawaii Music Awards, and travelled back to Honolulu the next day to place first in the final round of the International Chopin Competition of the Pacific. He performed recitals in Poland in 1997 at the Fryderyk Chopin Society of Warsaw and Żelazowa Wola (Chopin's birthplace). On 3 October 1997, the third anniversary of beginning piano studies, he performed a recital of Chopin's Études Op. 10 and 25 at the Academy of Arts in Honolulu.