But one year into the job, she is struggling under the weight of a mediocre report card that has dented the fortunes of comedian Beppe Grillo's opposition party less than a year from national elections.
A photogenic lawyer plucked from obscurity to become the poster girl for M5S's national ambitions, Raggi, 38, promised to improve failing public services, weed out endemic corruption and start repairing crumbling infrastructure in the capital.
But 12 months later, ordinary Romans can see no signs of progress as the city's international image becomes increasingly tarnished by negative commentaries on rubbish-strewn streets and trees keeling over for lack of maintenance.
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Photo: Andreas Solaro/AFP
On Viale della Moschea, next to the biggest mosque in Western Europe, and several other streets, the potholes are so bad the speed limit was slashed 10kmh (6mph) last week, on safety grounds.
Meanwhile the image of Raggi's administration has become pock-marked by the same kind of allegations of cronyism and sleaze that undermined its predecessors.
"Nothing has changed. Rome's problems remain the same only with time they're getting worse," says Mariano, a restaurateur in the trendy downtown district of Trastevere.
Dirty old town
Elected with just over two thirds of the vote in the run-off second round of last year's mayoral election, Raggi now has a disapproval rating at the same level.
And according to political expert Giovanni Orsina, she is regarded by her own party as more of a liability than an asset.
"Raggi speaks little, appears little, and M5S tries to avoid discussing Rome, which is a smart move - don't do anything to attract attention to what's happening," the professor at Rome's LUISS university told AFP.
Raggi's staff did not respond to AFP's requests for comment from her or a spokesperson.
Italian commentators have linked Raggi's woes to M5S's weaker-than-expected performance in this month's municipal elections.
"I voted for her in the second round last year, not with any great conviction but with a little bit of hope," says city resident Massimo.
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"I thought we'd have seen some progress after a year. But I have never seen a city as dirty as Rome is at the moment."
Co-citizen Annamaria's biggest gripe is the "very, very bad" state of public transport, with overcrowded buses struggling to cover the service needs of the city's sprawling suburbia.
"Nothing has changed. I hope she can sort it out. She's got to give it everything she's got," she told AFPTV.
Facebook page Rome fa schifo (Rome is disgusting) documents levels of degradation in the capital.
Broad backing lost
Raggi got off to the worst possible start. Her victory was anticipated but she still took months to put together a team amid serial resignations.
In December she was forced to apologise for trusting one official she handed a plum role after he was arrested for suspected corruption. And she is still without a chief of staff.
Invariably referred to as a fiasco, the situation at the Michelangelo-designed City Hall contrasts sharply with the positive impression made by Chiara Appendino, another M5S mayor who won power in Turin on the same night as Raggi.
Turin mayor Chiara Appendino. Photo: Marco Bertorello/AFP
"You can say the report card is catastrophically bad from every point of view," said Orsina. "There's no leadership team, the council does nothing. It is like a temporary administration dealing with issues on a day-to-day basis."
Fabrizio Ghera, head of one of the opposition groups in the city council, the right-wing FDI, says: "Not filling the potholes, cleaning the parks, pruning the trees: it's like a choice has been taken to do nothing.
"It is obvious the mayor has lost the broad backing she had in Rome."
Raggi's Five Star administration can at least claim credit for one decisive action: but pulling Rome out of the bidding for the 2024 Olympics did not go down well with everyone in the proud and ancient city.
By Ljubomir Milasin
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Photo: Giuseppe Cacace/AFP