In 2013, Kim reunited with Noh in romance melodrama That Winter, The Wind Blows (2013). He made his Chinese film debut in Young Detective Dee: Rise of the Sea Dragon directed by Tsui Hark, which became one of the highest grossing Chinese films of the year. He then starred in the thriller Miracle Hands by Kwon Ho-young. The same year, he took on his first historical drama Goddess of Fire which co-stars Moon Geun-young.
It was revealed on November 1, 2013, that Kim was dating his Goddess of Fire co-star, Moon Geun-young. On May 15, 2014, media outlets reported that they had ended their 7-month-long relationship. Agencies of both actors confirmed the news stating: "They did break up not too long ago but have decided to remain good friends and supportive colleagues".