Map - Rosarito Beach Municipality (Playas de Rosarito)

Playas de Rosarito Municipality (Municipio de Playas de Rosarito) is located in the northwestern part of the Mexican state of Baja California comprising part of the Tijuana metropolitan area. It lies just south of the city of Tijuana. Its municipal seat is the city of Rosarito. According to the 2020 census, the municipality had a population of 126,890 inhabitants. Its area is 513.32 km² (198.19 sq mi).

At the end of the 18th century, Spanish Dominican missionaries and friars gave the name of El Rosario to an indigenous settlement in the area. The town was part of the mission of San Miguel Arcangel de la Frontera, located a few miles to the south. The mission was founded on March 28, 1787 by the Dominican friar Luis Sales on the banks of the San Juan Bautista stream.

Over time, the name of El Rosario became Rosarito. After the Mexican–American War and the Treaty of Guadalupe Hidalgo, the new Mexican border lay no more than 30 km (18.5 miles) from Rosarito. This brought the development of the Rancho de la Tia Juana, which eventually grew into the city of Tijuana, the region's development hub.

Playas de Rosarito means "beaches of Rosarito".