Lee Kyu-hyung started acting in the Seoul Metropolitan Police Agency’s Whistle Theater while he was still a college student and has since performed in a long list of theater productions. In 2001, he landed his first big screen appearance in the film Kick the Moon. In 2013, he became part of the box-office hit The Face Reader, which won the Best Film trophy at the 50th Grand Bell Awards. In 2017, he was cast in a supporting role in the tvN series Forest of Secrets, which earned him a Best New Actor for TV nomination at the 54th Baeksang Arts Awards. That same year, he played a junkie in the well-loved tvN series Smart Prison Living. In 2019, he acted alongside Ji Sung, Lee Se-young, and Hwang Hee in the SBS medical drama Doctor John, which scored him an Excellence Award at the 12th Korea Drama Awards.
Lee Kyu-hyung majored in Theater Studies at the Dongguk Univerity. He developed a close friendship with actor Jo Seung-woo, whom he worked with in the television dramas Forest of Secrets and Life.