Opa-locka is a city in Miami-Dade County, Florida, United States. Spanning roughly 4.1 square miles, it is part of the Miami metropolita…Opa-locka is a city in Miami-Dade County, Florida, United States. Spanning roughly 4.1 square miles, it is part of the Miami metropolitan area of South Florida. As of the 2020 Census, the population was 16,463, up from 15,219 in 2010.