The Kim Soo Hyun Fan Union, which includes Daum Cafe Eucharis and DC Inside’s Kim Soo Hyun Gallery, has taken legal action against individuals spreading false and harmful rumors about the actor online. The fan union expressed concerns about ongoing defamation and false information circulating on social media and online platforms. They have decided to file a criminal complaint through their legal representation, Attorney Yang Tae Young from Law Firm Siwoo, at the Seoul Seongbuk Police Station to address the perpetrators under Korea’s Information and Communications Network Act.

Unlike insult charges that require the victim's direct complaint, third parties can pursue defamation charges. The fan union stressed that the legal action is not restricted to domestic fans and has international fan support. The initiative aims to protect the actor's rights and maintain a positive fan culture by denouncing personal attacks and defamatory content disguised as freedom of expression. The fan union has gathered substantial evidence, including malicious comments, edited images, and fabricated posts that have been circulating online for several months.

Gold Medalist, Kim Soo Hyun’s agency, also lodged a legal complaint on April 15, citing baseless allegations harming the artist's reputation. The agency filed defamation and insult charges with appropriate authorities. Additionally, legal actions were taken against the family of the late actress Kim Sae Ron and the operators of the YouTube channel Garosero Research Institute by Kim Soo Hyun's team. The lawsuits were prompted by claims suggesting Kim Soo Hyun was in a relationship with Kim Sae Ron from 2015 to 2021, starting when she was a minor. However, the agency clarified that the relationship only began after she came of age, from the summer of 2019 to the fall of 2020. Kim Soo Hyun also addressed the matter during a press conference on March 31, refuting allegations of being in a relationship with Kim Sae Ron when she was underage.