"The Thieves," featuring 10 Korean and Chinese thieves teaming up to steal a valuable diamond necklace at a Macao casino, drew 10,095,387 viewers in the first 22 days through Wednesday, data from the Korean Film Council showed.
The film opened on July 25 and is now being shown on 552 cinema screens across the country.
Directed by Choe Dong-hoon, who is known for "Tazza: the High Rollers" and "The Big Swindle," it stars top actors and actresses Jun Ji-hyun, Kim Hye-soo, Kim Yun-seok and Lee Jung-jae.
It became the first Korean film to break the 10 million mark since "Haeundae," a 2009 disaster drama directed by Yoon Jae-gyun.
The four other films to reach the mark are "Silmido," "Taegukgi," "The King and the Clown" and "The Host."
"The Host," a 2006 action-packed thriller by director Bong Jun-ho, drew the most viewers at 13 million.