The couple announced their engagement only on Tuesday.
Preparations for the wedding were carried out in secret, with guests told of the place and time only yesterday.
A local media outlet reported that the two met through mutual friends at a networking event, and that they have been seeing each other since the end of last year.
The venue was guarded by private security guards hours, preventing a group of reporters from getting a glimpse of the couple.
Rain, 34, and Kim, 37, started dating in 2012, with news of their romance becoming public on Jan 1, 2013.
"I am ready to be a good husband and a man as the head of a household.
She (Kim) stood by me through thick and thin," he was quoted to have wrote.
SEOUL (Korea Herald/Asia News Network ) - Love is in the air for the stars of the 2015 K-drama The Gang Doctor.
Following its leading lady Kim Tae Hee's marriage announcement with singer Rain on Tuesday (Jan 17), its leading man Joo Won confirmed on Wednesday that he is in a relationship with K-pop star Bo A.
In celebration of the new couple, Park sang Only You, a song he had written for his own wife.
Also there were actor Ahn Sung Ki, who is Rain's godfather; rapper Psy; Park Joon Hyung of pop group g.o.d.; and Kim's university classmate Lee Honey.
They had reportedly been preparing to say "I do" since their families met last November.