The exclusive world of high-end residential real estate is often narrowed to Manhattan or Beverly Hills — but South Florida cannot be counted out.

Miami-Dade County may not have the panache of a Hollywood star’s new estate or a Upper West Side skyscraper, but its selling environment — once synonymous with bust — is enjoying a boom again.

Late last month, a Miami penthouse sold for a record $25 million. Meanwhile, a developer’s 10-bedroom home on Indian Creek Island that has been listed at $52 million has gone under contract, brokers said.

If that deal closes, it will very likely top the record for a residential property sale in Miami-Dade County, real estate agents note.

The record is currently held by a hedge-fund billionaire who bought an Indian Creek home in March for $38.4 million.

“Everything is kind of selling now,” said Jill Hertzberg, a Coldwell Banker agent in Miami. “You wonder how long it will last.”

Southwest Florida real estate agents are asking the same question. Since the start of the year, luxury homes priced at $1 million or more have been selling briskly.

In February, sales of $1 million-plus homes in Sarasota, Manatee and Charlotte counties were up 48 percent from a year ago. In March, in Sarasota County, seven-figure sales jumped 48 percent over the same month in 2011.

Notable recent sales include a $7.1 million deal for a 6,618-square-foot property on Lido Shores, and a $5.77 million transaction for a 7,722-square-foot residence on Casey Key, which marked the largest real estate sale on the tony Nokomis key this year.

“I call it the ‘big thaw,’ and it’s resulting in more activity than we’ve seen since 2005,” said Michael Saunders, chief executive of the real estate brokerage firm that bears her name.

And more high-octane deals may be in the offing. Saunders’ firm last month listed Little Bokeelia Island, a 104-acre, private island in Charlotte Harbor, for sale at $29.5 million.

If a sale nets anything close to the listing price, it would set a sales record for Sarasota, Manatee, Charlotte and Lee counties for a single residential property.

The current record in Southwest Florida was set last year, when a Longboat Key home sold for $17.5 million.

Enormous price tags

The pending sale on Indian Creek — home to crooner Julio Iglesias and others among the region’s famous, or at least rich — is the latest in a string of high-end homes that have sold in Miami over the last three months.

All of the sales have been over $10 million, prompting new listings carrying enormous price tags. A 21,746-square-foot home on Indian Creek recently went up for sale for $45 million, and a New York developer just raised the listing price on his penthouse at Continuum towers, in Miami Beach, to $39 million — from $35 million — to be “in line with the market,” said Dora Puig, the listing agent.

“This has been a market-moving year for Miami Beach,” Puig said.

It wasn’t always like this.

Since 2006, when housing prices peaked, Miami has been widely viewed as the “poster child for distressed real estate,” with two-thirds of all sales being distressed as recently as 2010, said Jonathan J. Miller, the president of Miller Samuel, a real estate appraiser.

But dramatic price jumps have occurred. The average sale price for the highest 10 percent of homes rose 22.1 percent over the past year, Miller said.

The run of big sales started in December, with a Setai Resort and Residences penthouse that sold to a Chicago hedge-fund billionaire for $21.5 million, a record at the time.

“That lit the fuse,” Puig said.

On Indian Creek, one of the most exclusive communities in the country, four lots and homes have traded since March. In all, 32 homes surround a golf course.

Besides Iglesias, residents include Brazilian supermodel Adriana Lima, former Miami Dolphins head coach Don Shula, and billionaire investor Carl Icahn. Iglesias recently bought a nearly two-acre lot for $15.2 million; he now owns nearly 7 acres on the island.

Some believe the buying spree is caused by the realization that one day soon there won’t be any more waterfront property on which to build new trophy mansions.

“The future of extremely high-end real estate in Miami Beach,” said Nelson Gonzalez of EWM Realtors, “will be land.”