Yong Tsu Kiong, 48, ran a match-making firm but he also arranged fake marriages on the side.
Last month, the Singaporean was jailed for 11 months and fined $10,000 - the harshest sentence meted out to a sham marriage middleman so far - the Immigration and Checkpoints Authority (ICA) told The Straits Times.
Yong collected $26,000 for fixing three marriages of convenience before he was caught.
In the first case, Vietnamese Tran Thi Thuy Loan, 23, came to Singapore as a tourist but worked illegally as a KTV hostess, earning $100 a day. She wanted to stay longer and earn more money.
She was introduced to Yong, who charged her $9,000 to find her a husband. He then paid Koh Kian Joo, a 55-year-old odd job worker, $5,000 to marry Tran.
In another case, Chinese national Wu Yuhan, 23, wanted to look for a job in Singapore. She was introduced to Yong, who told her he could arrange for a Singaporean to marry her as that would help in her application for a work permit.
Wu gave Yong $13,000; of this, $5,000 went to security guard Yeo Tiong Poh, 48, to marry her.
No sex was involved between the couples in both cases.
In the last case, cleaner Toh Choon Seng, 37, gave Yong $4,000 to help him find a Vietnamese bride. He was then introduced to Pham Thi Linh Trang, 26, and the couple registered their marriage about a month after meeting.
Pham got $2,000 from Yong for marrying Toh. But Pham, who is said to be in the vice trade, did not live with Toh. She stayed in hotel rooms booked by her boyfriend and with other friends.
Toh really wanted a wife, but Pham just used the marriage to enable her to stay on in Singapore.
While Toh was not charged with entering into a marriage of convenience, he confessed to lying to the ICA that Pham lived with him.
He was jailed six weeks for making a false declaration. Pham and the others were jailed between six and eight months each.
Assistant Superintendent Yeo Ting Haw, from the ICA enforcement division, said the authority looks at the couple's intention for marriage to determine if the union is a sham, and investigates all cases thoroughly.