Hoverlab, a South Korean news commentary site on YouTube, claimed that the actor and the late actress Kim Sae-ron had been in a six-year relationship since she was 15 years old.

Kim Soo-Hyun was named a Prada brand ambassador in December 2023. He also attended the company's fall 2025 men's ready-to-wear runway show in Milan. The latest controversy around dating a minor Kim Sae-Ron is however leaving a deep impact on his personal and professional image along with his brand value.

According to Goldmedalist – an agency established by Kim Soo-hyun and his cousin – the actors dated from the summer of 2019, after she became an adult, to the autumn of 2020. Kim Sae-ron was born in July 2000, while Kim Soo-hyun was born in February 1988.