The Jazz Ensemble is comprised of students in grades 9-12 and meets before school from 7:45AM-8:45AM, Monday through Friday. Throughout this course, students develop many skills including improvisation, analysis, ear training, and performance.

Every year, John Adams hosts Jazz Soundsations, a two day district-wide jazz festival that invites clinicians to the school to work with almost every middle and high school jazz ensemble and then ends with a performance in the evening. The high school also hosts a local fundraiser called, Big Band Bash. At this event, the Jazz Ensemble performs multiple sets of jazz tunes for the community to raise money for the band program.

While the Jazz Ensemble has hosted events at the school, the group has also performed at multiple festivals in state, including those hosted by Ball State University, Purdue University, the Indiana State School Music Association (ISSMA), to name a few. Furthermore, the Jazz Ensemble has traveled out of state, including New York in 2007 and to Michigan for the Western Michigan University Jazz Festival.