Sebastian's first major performance as a piano soloist was of his composition Concertino for Piano and Orchestra with the Tokyo Symphony at the age of 9. Sebastian obtained his B.M. in Composition from the Curtis Institute of Music & an M.M. in Composition from the University of Southern California. From '16-'18, Sebastian was the Resident Composer for the Louisville Orchestra.
Sebastian is the youngest three time BMI Student Composer Awards recipient. He received his first award at the age of 14 (receiving the Carlos Surinach Prize that year for being the youngest recipient), his second award at the age of 17, and third award at the age of 19. BMI has reduced the maximum amount of awards per individual from three to two.
Sebastian's compositions have been performed by the Detroit Symphony Orchestra, the Philadelphia Orchestra, the Tokyo Symphony Orchestra, the Pacific Symphony, the Britt Festival Orchestra, the Louisville Chamber Choir, the NouLou Chamber Players, the Louisville Ballet, and the Louisville Orchestra.
Between Heaven and Earth, based on oil paintings of visual artist Vian Sora, premiered on February '18, performed by the Louisville Orchestra & Louisville Chamber Choir at the Kentucky Center in Louisville, KY.
Cryptogenic Infrastructure Fantasy (C.I.F.), for violin, clarinet, piano, and timpani, received its premiere in July '18 at the ChamberFest Cleveland, by Diana Cohen on Violin, Franklin Cohen on Clarinet, Alexander Cohen on Timpani, and Roman Rabinovich on Piano. Performed at the Maltz Performing Arts Center in Cleveland, OH. C.I.F. received its second performance at St. Stephen's Anglican Church in Calgary, Canada, in December '18.
He is Louisville Orchestra’s first-call pianist. He worked the summer '22 Britt Orchestra Season as Orchestral Pianist following the premiere of his Piano Concerto. He is an instructor in the piano conservatory at the Orange County School of the Arts. Sebastian freelances around Orange County & Los Angeles as a keyboardist. His publishing company is Sebastian Press, registered under the American Society of Composers, Authors, & Publishers (ASCAP).