The agreement includes a schedule for Sylvester Mwendwa and Elijah Kimani to live in her house, and states both will help raise any children. The woman has been having affairs with both men for four years, the British Broadcasting Corp. reported Monday.
A community policing officer said the two men were persuaded to joint-marry the unidentified woman after he saw them fighting over her, the local newspaper Daily Nation reported.
Kenyan family lawyer Judy Thongori said the law does not explicitly forbid polyandry, the practice of a woman married to more than one man, asking "whether these people come from communities that have been practicing polyandry."
The BBC said polyandry is not practiced by any community in Kenya
Mwendwa acknowledged the arrangement may in in breach of the law, but he had decided to enter into a contract with Kimani and the wife to end the rivalry between the two men.
"Our arrangement is good as it sets boundaries and helps us keep peace," he said.