The 30-seat dining room at Ceetay, an Asian fusion restaurant that opened last month on Bruckner Boulevard in the Mott Haven section of the Bronx, could easily pass muster in a trendy neighborhood like Williamsburg. Mason jars double as light fixtures, and the menu is filled with oddities like “maple and eggplant beef.”

Across the street, three entrepreneurs have just signed a lease to open a coffee shop that will double as a tapas bar at night. One block away, first-time restaurateurs Michael Brady and Charles Said are celebrating the first anniversary of their restaurant and bar, the Clock. From there, patrons have a clear view of the “Grand Opening” sign that hangs in the window of the new print shop across the street.

Welcome to a slice of the borough that ranks as the city’s fastest-growing breeding ground for new businesses. Between 1991 and 2011, the Bronx saw a quadrupling in the number of new business incorporations to 4,690, according to a study by the Center for an Urban Future.

“Entrepreneurs big and small were realizing this was an untapped market,” said the center’s executive director, Jonathan Bowles, who noted that adding to that momentum is the borough’s rapid population growth in recent years.

Others attribute the boom to everything from some of the city’s lowest rents for commercial space to, paradoxically, the borough’s high unemployment rate. Joblessness in the Bronx stands at 14.1%, far above the citywide average of 10.1%, according to the most recent, non-seasonally adjusted statistics from the state Labor Department.

“Because of the high unemployment rate, people feel it’s the right time to start something,” said Jose Made, a loan consultant at Accion USA, which during the past year alone has provided microfinancing to 14 small business owners in the Bronx. “They have nothing to lose and something to gain.”

The bulk of the new enterprises in the Bronx are not the cutting-edge tech companies launching in areas like Brooklyn’s Dumbo or Manhattan’s Flatiron district. Up in the Bronx, the newbies run the gamut from bars, barber shops and 99-cent stores to accountants, beer brewers and home-based day-care centers. But the bottom line is the same as it is anywhere else: a new crop of enterprises producing jobs, services and products for area residents, and income for fledgling entrepreneurs.

Bronx entrepreneurs are also benefiting from an influx of people who have been priced out of Manhattan and are looking for the closest affordable thing. Mott Haven—in particular, a small slice bordered by 138th Street and Bruckner Boulevard to the north and south, and St. Ann’s Avenue and Third Avenue to the east and west—is a prime example.

“There’s an evolving demographic of people who are moving into the Bronx because they can’t afford Manhattan or Brooklyn,” said Marlene Cintron, president of the Bronx Overall Economic Development Corp. She boldly predicts the area around Mott Haven’s Clock Tower building will morph into “the new Williamsburg.”

Bargain prices

What’s helping to draw a crowd is low prices. The average sale price of a one- or two-family house in Mott Haven last year was $250,000, according to Jonathan Miller, president of Miller Samuel real estate appraisers. That is a mere fraction of the average in Harlem, the closest Manhattan neighborhood, where one- and two-family homes range from $1 million to $2 million.

“It’s worth the swim,” said Mr. Miller.

Similarly, rents for retail and commercial space in the Bronx are among the lowest in the city. In Mott Haven, retail rents can be as low as $1,600 a month for a 350-square-foot shop, according to business owners.

“I’m paying one-tenth of what I would pay to rent the same space in Manhattan,” said Amir Chayon, an Israeli-born actor who is co-owner of Ceetay.

Ms. Cintron also offered a relatively new reason the South Bronx could make a play for the tech startups as well.

“We’re better elevated,” she said, contrasting that to low-lying portions of the Manhattan’s Silicon Alley that lost power for days as a result of flooding caused by Superstorm Sandy. “This is where the future is. Tech companies won’t lose power.”