Singapore had already reported six cases in the first 12 weeks of this year, the agency's website shows. Last year, more than 400 people became infected with the virus, following discovery of the first case in August.
"Both cases are residents in the vicinity and from the same household," the agency said in a statement.
"Residents and stakeholders are urged to maintain vigilance and continue to eliminate mosquito breeding habitats."
There is no preventive treatment against Zika, but drug companies are rushing to develop a vaccine.
Although generally a mild disease, the virus is a particular risk to pregnant women as it can cause microcephaly - a severe birth defect in which babies are born with abnormally small heads and underdeveloped brains.
More about: #Singapore
