Like its neighbor Peñamellera Alta and most of the municipalities in the district, Peñamellera Baja has been characterized by a progressive population loss over the last century. In the first part of the 20th century, most emigration from Peñamellera Baja was directed overseas. In the second half of the century, people began to emigrate to other parts of Europe and to the Asturian industrial centers. Since the population peaked in 1930 at 4,910 inhabitants, there has been a significant decline in population, leaving the current population at 1,579.