Volodymyr Zelensky (L) and his wife Olena during a presidential election debate in Kiev. Fiel / AFP
Zelenska, 42, added that her husband, President Volodymyr Zelensky, and their two children tested negative.
"Today I've received a positive COVID-19 test result," she said on Facebook.
On Thursday, Ukrainian authorities said there had been an "alarming" rise in coronavirus cases as the country eases lockdown restrictions.
On Friday, the ex-Soviet country reported 29,753 cases and 870 fatalities. The Ukrainian president urged officials to urgently establish the reason behind a spike in new cases.
"Only the observation of security measures will protect us from the threat of getting sick and save our economy from the quarantine," he said.
President Volodymyr Zelensky and Olena Zelenska attend the enthronement ceremony of Japan's Emperor Naruhito in Tokyo. Reuters
The first lady said that she felt fine and was self-isolating. She said the positive test was a surprise as she and her husband have sought to follow social distancing rules and protected themselves.
But the 42-year-old leader came under fire last week when he appeared without a mask in a cafe during a visit to the city of Khmelnytsky in central Ukraine.
Some experts have said the uptick is due to an increase in testing.
Lockdown measures eased gradually in late May and early June with a resumption of public transport, including metro systems and long-distance and local train services.
Ukraine launched domestic flights on June 5 and will resume international flights on Monday.
The global death toll from the virus surged past 106,000 on Saturday, with the United States quickly becoming the epicentre of the pandemic that first emerged in China late last year.
At the climax of Holy Week for the planet's two billion-plus Christians, congregations were shuttered at home to avoid spreading the pathogen that has infected at least 1.7 million worldwide.
Some intensive care specialists are trying to hire more permanent staff. Others want to create a reservist "army" of medical professionals ready to be deployed wherever needed to work in wards with seriously ill patients.
Like millions of other Britons, the prime minister will be able to have a trim and a tipple on Saturday, when the country takes its biggest step yet out of coronavirus lockdown with the reopening in England of restaurants, pubs and hairdressers, along with secular and sacred venues including cinemas and church.
When the Civil Defence men reached the accident site, one of them recognised the car. To his horror, it turned out to be his father’s vehicle. His two sisters were also inside the vehicle.
His Highness Dr Sheikh Sultan Bin Mohammed Al Qasimi, Supreme Council Member and Ruler of Sharjah, on Thursday approved the second phase of Sharjah Education Academy, that aims to develop the professional capabilities of educational cadres and granting professional and university qualifications in the field of education.
Fog blanketed separate areas of the UAE on Thursday morning, and lasted 6 hours from 12am until 8am, due to a weak surface low extension with a weak high extension in the upper atmosphere.
A migrant specialist in the Gulf since 2010 has welcomed and hailed the commitment and dedication of the UAE and Philippine governments in addressing concerns surrounding household service workers (HSWs), resulting in the implementation of a progressive bilateral labour agreement