Eric Leroy Adams, a former New York City police captain whose attention-grabbing persona and keen focus on racial justice fueled a decades-long career in public life, was elected on Tuesday as the 110th mayor of New York and the second Black mayor in the city’s history.

Mr. Adams, who will take office on Jan. 1, faces a staggering set of challenges as the nation’s largest city grapples with the enduring consequences of the pandemic, including a precarious and unequal economic recovery and continuing concerns about crime and the quality of city life, all shaped by stark political divisions over how New York should move forward.

His victory signals the start of a more center-left Democratic leadership that, he has promised, will reflect the needs of the working- and middle-class voters of color who delivered him the party’s nomination and were vital to his general election coalition.

Mr. Adams, whose win over his Republican opponent, Curtis Sliwa, appeared to be resounding, will begin the job with significant political leverage.

He was embraced by both Mayor Bill de Blasio, who sought to chart more of a left-wing course for New York, and by centrist leaders like Michael R. Bloomberg, Mr. de Blasio’s predecessor. Mr. Adams was the favored candidate of labor unions and wealthy donors. And he and Gov. Kathy Hochul have made clear that they intend to have a more productive relationship than Mr. de Blasio had with Andrew M. Cuomo when he was governor.

The Associated Press called Mr. Adams’s victory 10 minutes after polls closed, reflecting the overwhelming edge Democrats have in New York City even amid signs of low turnout.

Observers of New York politics were awaiting results in two Long Island races for district attorney that tested suburban attitudes about the state’s recent criminal justice reforms. And in Buffalo, a fiercely contested matchup between India B. Walton, a democratic socialist and the Democratic nominee, and the incumbent mayor, Byron W. Brown, was getting national attention. The race was not expected to be decided on election night, in part because Mr. Brown waged a write-in campaign, and his votes were likely to require more scrutiny.

In New York City, the difficulties that Mr. Adams, 61, will encounter were apparent even as he celebrated his victory.

In one of the world’s financial capitals, workers are barely trickling back to their Midtown Manhattan offices. The tourism industry is suffering. Many of the city’s beloved restaurants and other businesses have closed for good. And even as Wall Street profits soar, the city’s unemployment rate stood at 9.8 percent in September, with job growth lagging behind the pace that some economists had predicted last spring.

Mr. Adams will also inherit a budget gap of about $5 billion that will require immediate action, said Andrew S. Rein, president of the nonpartisan Citizens Budget Commission. There will also be contracts to negotiate with city workers and, eventually, the federal aid that helped pay for some city priorities will dwindle.

“Every decision has long-run implications,” Mr. Rein said. “If you start sooner, you can take care of it. When you’re in an emergency situation, it’s hard to make good decisions that are not painful.”

Mr. Adams has stressed that he plans to focus on rooting out inefficiency, but the scope of the fiscal challenges will most likely require more difficult choices.

He has made it clear that large companies have a role to play in shepherding the city’s recovery, and there are indications that he may have a far warmer relationship with business leaders than Mr. de Blasio, who was elected on a fiery populist platform.

“He’s restored confidence that the city is a place where business can thrive,” said Kathryn S. Wylde, who leads the business-aligned Partnership for New York City. “He’s demonstrated that he has the courage to, basically, be politically incorrect when it comes to dealing with the demonization of wealth and business.”

There is no issue the next mayor has discussed more than public safety.

Mr. Adams grew up poor in Queens and Brooklyn and says he was once a victim of police brutality. He spent his early years in public life as a transit police officer and, later, a captain who pushed, sometimes provocatively, for changes from within the system. That experience cemented his credibility with older voters of color, who may mistrust some officers while also worrying about crime.

During the primary, amid a spike in gun violence and jarring attacks on the subway that fueled public fears about crime, Mr. Adams emerged as one of his party’s most unflinching advocates for the police maintaining a robust role in preserving public safety. He often clashed with those who sought to scale back law enforcement’s power in favor of promoting greater investments in mental health and other social services.

Mr. Adams, who has said he has no tolerance for abusive officers, supports the restoration of a reformed plainclothes anti-crime unit. He opposes the abuse of stop-and-frisk policing tactics but sees a role for the practice in some circumstances. And he has called for a more visible police presence on the subways.

The public safety issue remained on the minds of some voters on Tuesday.

“Hopefully, since he used to be in N.Y.P.D., he could get everything amicable again with the city and the N.Y.P.D., because it’s been very dangerous out here,” said Esmirna Flores, 38, as she prepared to vote for Mr. Adams in the Bronx.

Yet other voters said Mr. Adams’s emphasis on policing stoked misgivings. And he will certainly face resistance on the subject from some incoming City Council members.

Tiffany Cabán, a prominent new member who was endorsed by the Democratic Socialists of America, said that on many issues, such as expanding bus and bike lanes, she was “ready to be collaborative.”

“Then you’ll see that there are times where there will be tension,” Ms. Cabán said. After emphasizing potential areas of common ground on public safety matters, she pointed to the prospect of Mr. Adams’s more assertive policing policies and added: “We’re going to be ready for a fight on those things.”

On the other side of the political spectrum, there are continuing tensions over vaccine mandates. Mr. Sliwa highlighted the issue, which has been difficult for labor leaders to navigate, and it appeared to fire up voters in conservative corners of the city in the race’s final days. The matter may be resolved by the time Mr. Adams takes office, but it underscores the extraordinary challenges that come with governing through a lingering pandemic.

There may also be battles over education. Mr. de Blasio recently vowed to begin phasing out the gifted program in the city’s schools, which puts children on different academic tracks and has been criticized for exacerbating segregation. The issue inspires passions among parents.

Mr. Adams has indicated that he wants to keep and expand access to the program, while also creating more opportunities for students who have learning disabilities, as he did. Mr. Adams, who speaks often about his own struggles with a learning disability, is a proponent of universal screening for dyslexia.

More immediately, he faces the task of filling out his government.

Throughout the campaign, Mr. Adams faced significant questions from Mr. Sliwa — and the news media — over matters of transparency, residency and his own financial dealings. The people he hires for his administration will play a significant role in setting the tone on issues of ethics and competence.

Asked what he was looking for in the powerful position of first deputy mayor, Mr. Adams said on Tuesday that his “No. 1 criteria” was “emotional intelligence.”

“If you don’t understand going through Covid, losing your home, living in a shelter, maybe losing your job, going through a health care crisis, if you don’t empathize with that person, you will never give them the services that they need,” he said.

For some voters who went to the polls on Tuesday, it was Mr. Adams’s own life experience that compelled them to turn out.

Mark Godfrey, a 65-year-old Black man, said Mr. Adams’s rise showed that “there are subtle changes that are occurring in the U.S.” related to racial equity and representation.

“He’s been on both sides,” Mr. Godfrey said of Mr. Adams’s experiences with law enforcement. “He’s been a survivor, and he’s been part of the change.”

Reporting was contributed by Nicholas Fandos, Nicole Hong, Jeffery C. Mays, Julianne McShane and James Thomas.