Shin Sung-rok had wanted to become an actor since high school, so when an injury cut short his career as an amateur basketball player (his brother is Shin Je-rok, formerly of the Anyang KT&G Kites), he decided to major in Theater and Film at Suwon University (though he later dropped out). Shin made his acting debut in 2003, but found it difficult to find acting jobs since directors were reluctant to cast the 187 centimeter-tall aspiring actor in supporting or minor roles. Thinking he would have a better chance if he gained more acting experience and honed his craft on the stage, Shin switched gears and joined the theater company Hakchon.
When Shin performed in his first musical Moskito, there were only 20-25 audience members in the 500-seat hall. Despite feeling depressed and frustrated, he said the experience made him strong and helped him become an actor with plenty of guts.
While doing the musical Dracula, Shin was cast in his first substantial onscreen role, in the risqué cable drama Hyena (2006). Supporting roles in dramas and films followed, notably in Thank You (2007) and My Life's Golden Years (also known as All About My Family, 2008). He also appeared on season 1 of the MBC dating reality show We Got Married as a "fake couple" with female comedian Kim Shin-young.
Mainstream breakthrough still eluded Shin, but in theater his star was rising. In 2007 Shin was picked from 400 auditionees for the lead role Solomon in Dancing Shadows, a musical adaptation of the realist play Forest Fire by celebrated Korean playwright Cha Beom-seok. He later received a Best New Actor nomination from the Korea Musical Awards.
As Shin starred in one hit musical after another, he continued to impress critics with his acting performances, his strong and powerful baritone vocals and his delicate and clear alto notes. He is now considered a top musical star, even drawing fans from outside Korea to his shows.
Definitely Neighbors (2010) further boosted his TV profile; for his role as a difficult chef who falls in love with an older divorcee, Shin won Best Supporting Actor in a Weekend/Daily Drama at the 2010 SBS Drama Awards. But his most popular drama yet was the romantic comedy My Love from the Star (2013), in which he appeared as a villainous businessman. This was followed by supporting roles in the 2014 series Trot Lovers (as a talent agency CEO), Liar Game (as the host of a reality show), and The King's Face (as a face reader).
Despite branching out to film and television, Shin has maintained that his heart will always belong to the stage. "I feel more affection toward the stage (than TV). I think it is the stage where actors learn life and understand the meaning of acting. It is where I learned how to act and where I gained confidence. I think the core of my life will remain on the stage" (The Korea Herald, 2007). "The musical is like my old home and it made me what I am now, so I can't stop performing the musicals however busy I get. I always covet a good musical and try to do it because a good musical won't wait for me [...] I like musicals because I can communicate with the audience. Also, TV dramas and films are good at portraying characters in detail. I will show better performances in my new work. [...] I hope many become familiar with me through more diverse channels and come to see the musicals and boost musical culture. Personally, I want to let my name become widely known to general audiences." (The Korea Times, 2009)
Shin began dating ballerina Kim Joo-won in 2011; Kim was a principal dancer with the Korea National Ballet for 15 years from 1988 to 2003, and currently teaches at Sungshin Women's University. The pair broke up after four years of dating in August 2015. In June 2016 he married a non-celebrity office worker