Jang Ki-young entered the entertainment world as a model in 2012. Two years later, he had a cameo in the 2014 SBS medical romance drama It’s Okay, It’s Love. His brief appearance in the series created quite a buzz in South Korea despite him having no lines in it. In 2017, he landed a supporting role in the KBS2 romantic fantasy drama Go Back Spouses. His work in the series earned him a Best New Actor nomination at the 2017 KBS Drama Awards. In 2018, he took on the role of a cold-hearted loan shark in the tvN drama My Ajusshi, which won him Best New Actor in the APAN Star Awards. That same year, he landed his first TV leading role in the MBC melodrama Come Here and Hug Me, opposite Jin Ki-joo. He was named Best New Actor for TV at the 55th Baeksang Arts Awards for his performance in the drama. He also received an Excellence Award and the Best Couple Award with Jin Ki-joo at the 2018 MBC Drama Awards for the series.

Jang Ki-young contributed his vocals to the official soundtracks of some of his dramas such as The Liar and His Lover and Come Here and Hug Me.

Jang Ki-young enlisted for his mandatory military service on August 23, 2021.