Breña Baja is a municipality located on the eastern side of the island of La Palma within the province of Santa Cruz de Tenerife in Spain. Situated in the Canary Islands, this administrative division plays a significant role in the regional governance structure of the archipelago. The municipal office, known as the ayuntamiento, is situated in the town of San José, which serves as the central hub for local administration and civic affairs.

The area was historically known simply as Breña until the seventeenth century when it was divided into two distinct entities: Breña Alta and Breña Baja. This division marked a pivotal moment in the region's development, establishing separate administrative boundaries that persist to this day. The historical evolution from a single entity to two municipalities reflects the growing complexity of settlement patterns and local governance on La Palma.

The municipality features eight subdivisions or parishes, each contributing to the diverse character of the area. Notable districts include San Antonio, San José, La Polvacera, Los Cancajos, Las Ledas, El Socorro, La Montaña, and El Fuerte. The coastal resort town of Los Cancajes stands as La Palma's second largest resort, offering significant tourism infrastructure. Additionally, part of La Palma Airport, formerly known as Mazo Airport, is located within the municipal boundaries.

Visitor appeal is largely driven by the coastal resort areas and the presence of the airport, which facilitates access to the island. The town of San José, with an elevation of 300 meters, serves as the administrative center and a focal point for local life. The distribution of population across various parishes suggests a spread of residential and commercial activities throughout the municipality, catering to both locals and tourists seeking the unique environment of La Palma.

The population of Breña Baja is recorded at 6,159 as of 2025. Historical demographic data from 2005 indicates that San Antonio had the largest share with 1,128 persons, followed by San José with 1,042 persons. Other subdivisions such as La Polvacera, Los Cancajos, and Las Ledas have smaller populations, reflecting the varied settlement density across the eight parishes that comprise this eastern La Palma municipality.