Riho was born in Toronto, Canada and started composing while enrolled in high school. He completed undergraduate studies in composition at the Estonian Academy of Music and Theatre in Tallinn, Estonia, as a pupil of Helena Tulve and René Eespere, while enhancing his connection to his Estonian heritage. He recently completed his Master's degree at the University of Toronto under Christos Hatzis, where he was the recipient of an Ontario Graduate Scholarship and the prestigious Tecumseh Sherman Rogers Graduating Award.
In 2011 Riho was awarded the highSCORE Prize in Pavia, Italy and the Karen Kieser Prize in Canadian Music, and was selected as one of four Canadian composers under the age of 35 to take part in the Génération 2012 project, which was toured in 8 cities across Canada. In April 2012 he won the Villiers Quartet Competition in the UK, based on an audience vote, and most recently, Riho was selected as the 2013-2014 recipient of the Presser Graduate Music Award.
Riho has composed a significant amount of choral music that has been performed by groups in Estonia, such as the Tartu Academic Women's Choir, the Tallinn Chamber Choir and the vocal ensemble Heinavanker ("Haywain"). He was also commissioned to write a work for chamber choir and percussion quartet, performed by the Larkin Singers and the TorQ Percussion Quartet in Toronto in April 2013.
Riho is currently studying as a professional diploma student at the Curtis Institute of Music in Philadelphia, with David Ludwig.