Gov. Andrew M. Cuomo announced on Wednesday that the prohibition on indoor dining in New York City would be lifted on Sept. 30, giving a boost to the city’s recovery from the pandemic and ending its status as one of the few places in the nation with a ban.

The governor’s decision to allow restaurants to have indoor dining at 25 percent capacity will be a major milestone in the coronavirus crisis in New York City, signaling to tourists and residents that the city is slowly returning to normal.

Still, the reopening will likely not be enough to save some restaurants, battered by the combination of the coronavirus, the economic crisis and the reluctance of many Americans to socialize in proximity to others, particularly as colder weather limits outdoor dining.

The move came more than two months after the governor and Mayor Bill de Blasio halted a plan to permit indoor dining at restaurants, citing worries about a resurgence of the coronavirus, which has killed more than 30,000 people in New York State. Even so, the reopening announcement left some concerns still percolating at City Hall, as Mr. de Blasio had favored a longer lag between a planned reopening of schools and the city’s indoor dining.

But with the infection rate in the state stabilized at under 1 percent for more than a month, the governor said he would ease some restrictions at a time of desperation and frustration for the city’s restaurant industry, which has watched some venerable and venerated eateries fail and losses mount for others even as neighboring states and regions reopened their dining rooms.

“Because compliance has gotten so much better, we can now take the next step,” the governor said.

Under the governor’s plan, restaurants would be permitted to use a quarter of their indoor tables just as the fall weather is likely to put a chill on outdoor service, which began in June and has allowed many restaurants to make game attempts at staying afloat.

On Wednesday, many of those manning kitchens — from greasy spoons to fine dining — voiced measured relief that they would soon be able to welcome patrons inside, as well as rehire some staff, as the city grapples with an unemployment rate of nearly 20 percent.

“With 25 percent plus outdoor, I can hire back 50 percent,” said Jean-Georges Vongerichten, the celebrity chef whose flagship restaurant, Jean-Georges, is in Columbus Circle.

The move carries substantial financial and health risks for New York, the one-time epicenter of the pandemic, and still home to some of the most stringent regulations regarding the disease, including a 14-day quarantine for visitors from dozens of other states.

New York City, a world capital of dining and entertainment, remains in a defensive crouch, with Broadway shuttered, movie theaters and clubs closed and many cultural institutions operating under strict capacity restrictions.

The caution seems warranted: State officials said about 10 percent of coronavirus clusters outside of New York City have been tied to bars and restaurants, a source of infection second only to large gatherings. Bars and restaurants have also fueled outbreaks nationwide and across the world.

The reopening will also come shortly after New York City’s public schools — the nation’s largest school system — will welcome students back inside on Sept. 21, another complex and fraught experiment that has already been delayed once by Mr. de Blasio.

Local officials, wary of returning to the nightmare of March and April, when the disease was killing hundreds of people a day, were reluctant to do anything that would put the city in peril, and were prioritizing reopening schools rather than indoor dining.

The timing of Mr. Cuomo’s announcement, which came after months of debate at a state and city level, caught some by surprise, coming just hours after Mr. de Blasio suggested a decision on dining was still being fine-tuned.

One plan under discussion at City Hall called for putting indoor dining off until schools had been reopened for at least a month and there had been no substantial uptick in the positivity rate, according to one city official familiar with the plan. But the announcement by the governor, who has authority over such decisions because of expanded powers granted to him during the crisis, rendered that approach moot.

Mr. Cuomo, a third-term Democrat who has frequently sparred with Mr. de Blasio, had acknowledged that he was under intense pressure from restaurateurs to reopen indoor dining spaces, noting on Wednesday that “a restaurant is not just the restaurant owner, a restaurant is the kitchen staff, the wait staff.”

“Restaurants also pose a possible risk,” he said, adding, “But there is also a great economic loss when they don’t operate.”

The combination of students in schools and patrons in dining rooms will likely heighten anxiety about the possibility of a second wave of coronavirus infections for public health officials and experts, who said that reopening both in such quick succession comes with a substantial risk.

“I would like to understand the extent to which school reopening is contributing to a bump, or a spike, or lack thereof before moving on to another significant contributor to new cases,” said Denis Nash, an epidemiology professor at the CUNY School of Public Health, who has in the past worked for the New York City Department of Health and Mental Hygiene.

He added, “If it’s all going on at the same time, it makes it difficult to tease apart and know what’s driving any bumps we may see,” he said, referring to possible upticks in cases.

Mr. Cuomo said that state would evaluate infection rates and other data after the Sept. 30 reopening, with an eye toward increasing capacity to 50 percent by Nov. 1, perhaps sooner.At the same time, he also warned that any spike in infections could lead to sudden closures via an “emergency pause button.”

Even as other parts of the state reopened their dining rooms in late spring, the city’s indoor tables remained closed. For weeks, many restaurant owners had complained about a split reality at the city border — on one side indoor dining, on the other, a ban. Some sued, questioning why there was a continuing bar on indoor dining in the city even as virus levels in both the suburbs and the city were virtually the same.

Nor will the allowance be a panacea. Even with indoor dining permitted, not all restaurants may do it, since many are concerned about safety, and some have spaces so small that capacity restrictions may not make it worthwhile.

“I know I can make it work at 50 percent, but the expenses of getting it up and running, versus the revenue, my gut tells me that it will not work at 25 percent,” said Eric Ripert, the chef and an owner of Le Bernardin, on West 51st Street.

There is also the question of whether diners will feel comfortable returning to indoor spaces: A recent poll by the Siena College Research Institute found that 58 percent of New Yorkers, and 65 percent of city residents, said they were still not comfortable with dining indoors in a restaurant. More than 70 percent of both city and state residents also said they were not yet comfortable having a drink at a bar.

Without a government relief package specifically for restaurants, about 64 percent of New York restaurants said they are likely to close by the end of the year, according to a recent survey from the New York State Restaurant Association.

“I think at the end of September, you are going to see a lot of for-rent signs on New York City restaurants,” said Cindy Smith, an owner of the Mermaid Inn, which has already permanently closed its original East Village location, but is hanging on for now at its three other Manhattan locations. Only one is open for outdoor dining.

Under the governor’s plan, restaurants will be required to check customers’ temperatures and collect contact information for one person in each party. Diners will be required to wear face coverings when not seated, and bar service will not be allowed. Closing time will be midnight.

Russell Jackson, the chef and owner of Reverence, a tasting menu restaurant on Frederick Douglass Boulevard in Harlem, said he has been staying alive with takeout and delivery, which were still allowed after Mr. Cuomo ordered bars and restaurants to close in March.

“As this is going to settle in that we’re all going back to work, I know all of us are going to start freaking out,” Mr. Jackson said. “We shifted this restaurant to be a completely different animal over the past six months. Now we have to change all the protocols. It’s going to be an enormous adjustment.”

Mr. Cuomo said that the city will provide 400 code enforcers, which could include New York City police officers, in addition to oversight from the New York State Liquor Authority, New York State Police and other agencies. But he also invited diners to anonymously report restaurants where they believe the 25 percent capacity is being violated.

On Wednesday, Mr. Cuomo acknowledged that the infection rate might increase with “more people at work, more people at schools, more restaurants, more people on the street,” though he said there was no “hard number” that would force the state to retreat.

“We’ll just watch it,” he said, “and see what we hear.”