Jin Gu made his acting debut in the 2003 SBS series All In, playing the younger counterpart of Lee Byung-hyun’s character. In 2006, he became part of the neo-noir action film A Dirty Carnival, which earned him Best New Actor nominations at the 27th Blue Dragon Film Awards and the 43rd Baeksang Arts Awards. In 2007, he starred in the horror film Epitaph, which won him Best New Actor at the 31st Golden Cinematography Awards. In 2009, he joined director Bong Joon-ho’s critically acclaimed thriller film Mother, which scored him numerous acting recognitions including Best Supporting Actor at the 46th Grand Bell Awards and the 30th Blue Dragon Film Awards. In 2014, he acted alongside Choi Min-shik in the blockbuster epic action-war film Roaring Currents. In 2016, he played an elite special forces soldier in the hit KBS2 series Descended From the Sun, which took home the Daesang for TV at the 52nd Baeksang Arts Awards. He also bagged the Best Supporting Actor trophy at the 5th APAN Star Awards for his work in the series.

Jin Gu married his non-celebrity girlfriend in September 2014. They welcomed their first child in June 2015. Their second child was born in November 2016.