I followed the instructions from the Korea Canadian Embassy Website (in Seoul). Copy and pasted below. If you go to the website, there are more FAQ on sponsorship applications as well.
Getting married in Korea
Introduction
If you wish to get married while in Korea you can obtain a civil marriage under Korean law. Marriage is a civil procedure in Korea, and performing a religious ceremony only does not constitute a legal marriage. For your marriage to be legally recognized in Korea and hence, legally recognised in Canada, you and your fiancé (e) must be free to marry, must report and register your marriage to the appropriate civil authorities. While consular officials are not authorized to perform marriage ceremonies, we can, however, notarize necessary documents for a civil marriage in Korea.
Procedures
You must take the following steps to get married in Korea.
First both parties must appear in person with the documents listed below and complete three copies of the Affidavit of Eligibility of Marriage and three copies of Report and Certificate of Marriage. We will verify your documents and notarize the affidavit of eligibility of marriage.
Take the notarized copy of the Affidavit of Eligibility along with three copies of the completed Report and Certificate of Marriage to your local district office (Gu Cheong) for approval and signature by a Korean government official. The district office will keep one copy of the Report and Certificate of Marriage as a record.
Finally, bring two copies of the Report and Certificate of Marriage signed at the district office back to the Embassy for authentication. One of the parties can return or mail the documents to the embassy.
Required documents
Affidavit of Eligibility of Marriage
You need three copies, please view instructions for completing the form | PDF * (159 KB)
Report and Certificate of Marriage
You need three copies, please view instructions for completing the form | PDF * (164 KB)
For a Canadian citizen
Canadian passport
Proof of termination of any prior marriage(s) such as an original or certified of divorce certificate, annulment or death certificate of your previous spouse
If one of the parties is Korean
Korean ID (Ju Min Deungnok Jeung) or Passport
An original copy of Family Relationship Certificate (Gajok Gwangae;가족관계 증명서) and
Marriage/Single Status Certificate (Hone In Gwangae;혼인관계 증명서)
issued within 3 months. Translation is not required.
If one of the parties is not Korean
Passport
Affidavit of eligibility of marriage from his or her embassy
Proof of termination of any prior marriage(s) such as an original or certified of divorce certificate, annulment or death certificate of your previous spouse
*Please note that if your fiancé(e) is not Korean they should contact their embassy in Korea and seek advice on requirements on getting married in Korea.
Fee: Canadian $100 or equivalent Korean won, please View the exchange rate (Only cash is accepted).
Consular Service Hours
CANADIAN IMMIGRATION AND CITIZENSHIP REGULATIONS
Marriage to a Canadian citizen does not automatically confer permanent resident or citizenship status on the Korean spouse. To obtain permanent resident status, the Canadian partner must complete an undertaking to sponsor his/her spouse at a Canadian Immigration Centre in Canada. The Korean national must then meet all civil and medical requirements before a visa can be issued. Processing times vary according to individual circumstances, and the applicant is normally required to remain in Korea until such time as the Visa can be issued.
Learn about sponsoring your spouse for immigration to Canada.
