Han Seok-woo, 39, the head of the Libya unit of the Korea Trade Investment Promotion Agency, was rescued by Libyan forces after three days of captivity.
Authorities also arrested the four kidnappers late Wednesday in Tripoli, the Wall St. Journal reported.
The gunmen, members of a small armed group in the country, had not made any ransom demands, the Libya Herald said.
No further details about the case were released.
Han, who was taken from his vehicle early Monday morning, is in good condition at the South Korean embassy in Libya, officials said.