As a performer, Seelen is a founding member of the internationally recognized Ezekiel’s Wheels Klezmer Band, winning awards at the International Jewish Music Festival in Amsterdam, Brazil’s Bubbe Awards, and more. With Ezekiel’s Wheels and other ensembles, he has performed at major venues including the Kennedy Center, Tanglewood Music Center, and Jordan Hall, and internationally in China, Denmark, the Netherlands, Great Britain, Spain, and Canada.

Seelen is also the creator of New Klezmer Studios. This innovative remote learning initiative has taught klezmer music to students on five continents, including musicians from top institutions like Juilliard, New England Conservatory, Berklee, and Oberlin. He is a teaching artist with Arts for Learning Massachusetts. He has given workshops, masterclasses, and lectures at the Society for Ethnomusicology Annual Meeting, the University of Connecticut, Tufts University, and many more. In 2025, Seelen will join the faculty at New England Conservatory to teach klezmer music.

As a composer, Seelen’s recent works include 56 New Klezmer Tunes for Dancing (2023), Gathering Sparks (2022), and Di Khassene (2021), a multimedia song cycle created during the COVID-19 pandemic. He has received grants and fellowships from the Massachusetts Cultural Council, CJP Arts & Culture Fund, NEFA, and the Memorial Foundation for Jewish Culture.