The man, a doctor in a long-term relationship, initially approached authorities about adopting in the city-state but was told a homosexual couple were unlikely to get permission, according to court documents.
The couple travelled to the US where the doctor underwent procedures for in-vitro fertilisation and found a surrogate who agreed to carry his child for USD 200,000.
A son was born and as the biological father, the doctor -- who has not been identified -- was allowed to bring him back to Singapore to live with him. The boy is now four.
District Judge Shobha Nair said that the doctor and his partner were aware that procedures to help couples have children were available to only married couples in Singapore and there were no surrogacy services in the city-state.
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Gay marriage is not permitted in Singapore. Surrogacy is not explicitly banned although official guidelines prohibit the practice in assisted reproduction centres, according to the Straits Times newspaper.
"The applicant, a medical doctor himself, was acutely aware that the medical procedures undertaken to have a child of his own would not have been possible in Singapore," said the judge.
The child's welfare was not an issue in the case as he will continue to be well looked after by his biological father and he is not stateless as he holds American citizenship, the judge said.
She was not swayed by the arguments of the man's lawyers, Koh Tien Hua, Ivan Cheong and Shaun Ho, who denied he was seeking to adopt the boy to form what would effectively be a legally recognised gay family, the Straits Times said.