Kim Jae-young debuted as a model in 2011 before transitioning into acting in the 2013 sports film No Breathing. He then appeared in Iron Man in 2014 and in I Remember You in 2015, which both aired on KBS2. In 2017, he joined the main cast of the OCN romantic comedy My Secret Romance. He then became part of the 2017 OCN mystery-thriller Black. In 2018, he was cast in the tvN sageuk 100 Days My Prince and also starred in Olive’s Eun-joo’s Room. In 2019, he played one of the main characters in the SBS series Secret Boutique, which scored him a Best New Actor nomination at the SBS Drama Awards. That same year, he won Best New Actor at the KBS Drama Awards for his work in Beautiful Love, Wonderful Life. In 2021, he acted alongside Go Hyun-jung and Shin Hyun-bin in JTBC’s Reflection of You.