Hillsboro Beach occupies the south end of the barrier island locally known as Deerfield Beach Island, or Deerfield Cay, with the Atlantic on one side. Most of the town's area is water, and its land is well under half a square mile. Its only main road is a 3.2-mile stretch of State Road A1A called the Hillsboro Mile, nicknamed Millionaires' Mile for the large homes along it.
The town's first permanent structure was the Hillsboro Inlet Lighthouse in 1907, and it was incorporated by a special act of the Florida Legislature in 1947. The 2020 census counted 1,987 residents and 2,428 housing units, more than half of them vacant at the time of the count, which fits a population that has roughly doubled every winter since the town's early years.