2019–present: Comeback and international fame
Kim returned to television in December 2019 when he joined the tvN romance drama Crash Landing on You alongside Hyun Bin, Son Ye-jin and Seo Ji-hye. It became the highest-rated tvN drama and the third-highest-rated Korean drama in cable television history. Kim's portrayal of Goo Seung-joon, former fiancé of Yoon Se-ri (Son Ye-jin) and eventual love interest to Seo Dan (Seo Ji-hye), received positive reviews from audiences. His character's name "Goo Seung-joon" went on to trend at No. 1 in Korea's realtime search rankings, which he later described in an interview as incredibly rewarding.
In May 2020, Kim made a cameo appearance in his Crash Landing on You co-star Seo Ji-hye's drama Dinner Mate playing the role of her long-term boyfriend.
On June 5, 2020, it was confirmed that Kim would lead tvN's fusion sageuk drama, Mr. Queen alongside Shin Hye-sun playing the role of King Cheoljong. The drama aired from December 2020 to February 2021. On February 15, 2021, Mr. Queen became the seventh-highest-rated Korean drama in cable television history and the fifth highest rated tvN drama on record. The Korea Times article praised Kim's complex portrayal of the two-faced King and noted that he "left a deep impression on viewers with a heavy presence that took the center of the play." Kim contributed his vocals to the soundtrack with the song Like the First Snow; for which he also wrote the lyrics.
In September 2021, Kim signed with Story J Company followed by movie and drama casting news in 2022.
In January 2022, his agency confirmed that he will appear as a Detective in an indie film called Se2cret.
In 2023, Kim returned to television with MBC's Kokdu: Season of Deity opposite actress Im Soo-hyang playing dual role of a Grim reaper and doctor. Kim received praise for 'Perfectly portraying two conflicting characters' through a variety of charms. He also lent his vocals to the opening theme song of the drama titled I am.
In March 2025, Kim officially parted ways with Story J Company after his exclusive contract expired, ending a four-year partnership that began in 2021.
In May 2025, Kim signed an exclusive contract with Management Seesun, a newly established agency that also manages his Mr. Queen co-stars Shin Hye-sun and Cha Chung-hwa, marking a new chapter in his career.
