Onny Prihantono is currently the music director and conductor of both the St.Louis High School Choir and the Alouisia Choir. He has helped St.Louis High School Choir win three Gold Awards Category Championships in Mixed Youth, Equal Youth and Folklore at the Singapore International Choral Festival (SICF) 2017 and was awarded Grand Prix Champion of SICF in 2017. He has led the St.Louis High School Choir in becoming category champions and Grand Prix champions 17 times in 5 years, consecutively from 2014 to 2019. He also led the St.Louis High School Choir to reached 2nd position at the 1st Asia Choral Grand Prix in Cultural Centre of The Philippines in 2019, a competition among Champions of Asia.

He was a member of the East Java Youth Choir and the Gita Bahana Nusantara Choir Orchestra from 2004 to 2005. He later joined the Asian Pacific Youth Choir 2015 in Milan, Italy and Macau, China, performing as a Bass 2. In 2018, he rejoined the Asian Pacific Youth Choir in Kaili, China. Onny also attended conducting courses with Dr.Brady Allred, Prof.Theodora Pavlovitch, along with masterclasses with Avip Priatna, Dr.Masashi Kishimoto, Stephen Leek, Agastya Rama Listya, Richard Samuel Awuy, Indra Listiyanto, Agustinus Bambang Jusana, Yosafat Rannu Leppong, Evelyn Merrelita, and Ira Purnamasari.