"She incarnates the women of Ukraine with her boundless benevolence and extreme beauty," Oleksiy Goncharenko, an influential blogger, wrote of the slim 52-year-old mother of four, a cardiologist by training.
"A country with women like that is invincible!" Goncharenko, also a legislator from the southern city of Odessa, argued that the "Marina factor" helped spur millions of Ukrainians to vote for her husband, Petro Poroshenko, who garnered 54.7 percent of the votes in presidential elections late last month.
A change in style
As she was sitting in parliament this weekend for her husband's inauguration, an event televised around the globe, Marina Poroshenko seemed to signal that the new leadership in Kiev will mark not just a change in politics but also a change in style.
Instead of the ostentatious beehive hairstyles of past first ladies, she tied her hair in a simple bun, and she wore an understated but perfectly fitting blue suit.
Her compatriots seemed to like what they saw.
"She looks very much like a European woman," said Kiev resident Halina Pohranychna, reflecting the sense that for followers of the Poroshenko camp, "European" denotes all that is modern and sophisticated.
"The Ukrainians really need a first lady," she added.
"A lot depends on women, and Marina Poroshenko must help the president."
Marina and Petro Poroshenko have been married 30 years in what by all accounts has been a solid and happy relationship.
"I haven't regretted a single day," said Petro Poroshenko, three years Marina's junior.
She stands in particularly stark contrast with Lyudmyla Yanukovych, the wife of ousted pro-Russian president Viktor Yanukovych, who was, if possible, even less popular than her husband.
The main source of the rancour was a sole public appearance, a decade ago during the Orange Revolution, when Lyudmyla Yanukovych accused her husband's pro-Western adversaries of having consumed "drug-laced oranges".
Marina Poroshenko is unlikely to make similar political statements -- or any, for that matter.
In post-Soviet political culture, first ladies are not expected to get involved in affairs of state.
"Ukrainian society is very patriarchal, and attempts by the first lady to influence politics would get a very mixed reception," said Laryssa Kobelyanska, a well-known commentator.
The late Raisa Gorbacheva, wife of the Soviet Union's last leader Mikhail Gorbachev, has still not been forgiven by her compatriots for her very public interest in her husband's politics.
Marina Poroshenko, by contrast, gave up a promising career as a physician to devote herself to her family, and she has so far not divulged how she plans to fulfil her future role as first lady -- probably wisely so.
"What role she ends up playing will depend on the president. Unfortunately, we have inherited a traditional model where wives play the roles their husbands give them," Kobelyanska said.
Photos show Poroshenko visiting exhibitions and going to movie premieres with her husband, cooking food with her children, or performing religious services at a church, her face covered.
In rare interviews, she has restricted herself to commenting on family issues and children's education.
Despite the little that is known, Ukrainians like Ihor Diynychko, a Kiev entrepreneur, are overwhelmingly positive.
"I'm proud of our first lady. I'm happy that this beautiful and modest woman will represent Ukraine during Mr Poroshenko's visits abroad," he said.
"They are a strong couple, and that says a lot."