Originally a percussionist who was trained at the Oberlin Conservatory and Northwestern University, Kennedy lived in New York City from 1984 to 1999.
Kennedy had a long association with Spoleto Festival USA, leading the contemporary music component since 1990 and over time, assuming a wider role in the orchestra and opera programs.
From 2010 to 2023, he was the festival's director of orchestral activities and established the festival as a unique outpost in the U.S. for international opera, leading the American premieres of operas by Pascal Dusapin, Luca Francesconi, Philip Glass, Helmut Lachenmann, Liza Lim, Wolfgang Rihm, Kaija Saariaho, Toshio Hosokawa, and others.
He conducted the World Premiere productions of Paradise Interrupted (2015) by Huang Ruo as well as Omar (2022) by Rhiannon Giddens and Michael Abels.
As a conductor, he has led over 300 World and U.S. premieres, and conducted opera, orchestra, ballet, and new music projects with numerous organizations and festivals, throughout the U.S., Europe, and Asia.