The 56-year-old former city councillor from Brooklyn may excite few and leave Wall Street cold, but his progressive Democrat credentials and an absence of serious challengers is expected to propel him back into office for another four years.
Even with a low turnout, that will be no mean feat in the financial capital of the world's biggest economy, where the left-leaning politician presides over an annual budget of $85 billion, a city payroll of 295,000 and 8.5 million New Yorkers.
"He ain't the greatest but we have to have a Democrat," explained Peter Schnieder, 71, while casting his ballot in de Blasio's home district of Park Slope, an uber wealthy, progressive enclave of Brooklyn.
"He's not too bad. He's good enough to vote for."
The mayor won plaudits for achieving his signature campaign promise of launching universal pre-Kindergarten education for four-year-olds, and already rolling out a phased induction of three-year-olds.
The economy is doing well and crime is down, continuing the long-term trend under de Blasio's predecessors, the Republican-turned-independent billionaire mayor Mike Bloomberg, and Republican-turned-Trump-ally Rudy Giuliani.
On the other hand de Blasio's Trump-voting Republican challenger, 36-year-old Nicole Malliotakis, the daughter of a Greek immigrant father and a Cuban mother, has been left trailing in the dust. So has libertarian candidate Bo Dietl.
- 'Anybody against Trump' -
De Blasio has fended off federal and state investigations into fundraising -- no charges have been brought. An early confrontation with police -- having warned his bi-racial son to take "care" with officers, has long since dropped off the headlines.
So how has the mayor -- who physically towers over everyone else at six foot five (1.96 meters), is criticized for schlepping out to his Brooklyn gym and for lacking Bloomberg's charisma -- pulled off such a home run?
In an overwhelmingly Democratic city where 80 percent of the electorate voted for Hillary Clinton and Trump is despised, de Blasio has emerged as a symbol of opposition to the White House defending the rights of all.
"My hope is, starting today, if the people are with me, then we restore the idea this is a consistent Democratic and progressive town, and that goes on for many years to come," de Blasio declared Tuesday.
"Anybody who opposes Trump is OK with me!" agreed 69-year-old retiree Geraldine on Manhattan's Upper East Side, declining to give her last name.
And in a place where even dogs wear cashmere in winter, he has also come under fire over the rising homeless population and for his proposed millionaire tax, with which he proposes to overhaul the increasingly crisis-ridden subway.
- Homeless -
Scott and Jennifer Goodwin, a financial services worker and a stay-at-home mom, who are both registered Democrats said they voted Malliotakis in protest.
"It makes me sad I had to go against a Democrat," Jennifer told AFP. "I am seeing things I didn't see five years ago, the homeless are everywhere."
But in a city where whites -- De Blasio's most vocal opponents -- make up only 33 percent of the electorate, and 38 percent of New Yorkers are foreign-born, he is bolstered by strong support among Latinos and African Americans.
Malliotakis too has sought to capitalize on her own immigrant heritage.
"My parents came to USA with nothing. Today they voted for their daughter for mayor," she tweeted Tuesday. "That's the American Dream we must preserve."
Besides the mayoral election, two gubernatorial elections are also taking place Tuesday, in what could be bellwethers of sentiment a year after Trump's election and a year before the 2018 mid-terms.
In New Jersey, Democratic frontrunner Phil Murphy is expected to replace outgoing Republican and Trump ally Chris Christie.
In Virginia, Republican Ed Gillespie and Democratic Lieutenant Governor Ralph Northam are neck and neck.
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)