Jonja was born in Ho-Chi-Minh-City, Vietnam and grew up in Berlin, Germany where he received classical piano lessons from Chie Muto-Kumai at the age of 4, and later studied with Gesine Tiefuhr-Disselhorst.
As early as middle school, Jonja began conducting and co-leading the senior orchestra. Throughout his middle and high school career, he conducted, arranged, music directed, and played drums & percussion for various musical theater productions. He completed the International Baccalaureate Bilingual Diploma and holds the ECIS Award for International Understanding.
Jonja holds a BA in jazz piano and theater & performance from Bard College. Under the jazz program, he received instruction from Larry Ham and John Esposito, and conducting lessons from James Bagwell (The Orchestra Now, The American Symphony Orchestra). Jonja is a graduate student at NYU Tisch School of the Arts for an MFA in the Graduate Musical Theater Writing Program.
For the 2020 and 2022 productions of Broadway Cares/Equity Fights AIDS annual benefit concert Broadway Backwards, Jonja served as the Music Assistant, under the lead of Music Supervisor Mary-Mitchell Campbell (Mean Girls, The Prom, Tuck Everlasting) and Music Director Ted Arthur (Diana: A New Musical, The Prom).
His most recent shows include Show & Tell, Something Rotten, Dogfight, The Gauntlet, Songs For A New World, The Last Five Years, as well as many other shows. His original musical An Artist, Now (music by Jonja Merck, lyrics by Laila Perlman) was performed at the Fisher Center at Bard in February 2022.
Jonja is a proud member of MUSE (Musicians United for Social Equity) and a student in the MUSE One-On One mentorship program (2021 mentor Andrea Grody - The Band's Visit, Tootsie, and Suffs and 2022 mentor Elizabeth Doran - SIX, Mean Girls).