Madeira Beach is a city in Pinellas County, Florida, United States, bordered on the west by the Gulf of Mexico, and on the east by St. Petersburg. As of the 2020 census, the population was 3,895. The entertainment district of John's Pass is located on the Intracoastal Waterway. The city is often referred to by locals as Mad Beach. It is named after the Portuguese island of Madeira.