Sotrondio is a town in San Martín del Rey Aurelio, Asturias, Spain.

In September 2007, by a decree of the Principality of Asturias, it joined the adjacent El Entrego and Blimea to form a single population center, San Martin del Rey, as a homonymous municipality.

The population was 3,849 in 2009, fewer residents than in previous years, declining due to the crisis of industrial restructuring in the Asturian coalfield.

It is crossed by the Nalón River separating the Serallo neighborhood from the rest of the town.

It is the local parish church and was rebuilt by Duro Felguera after the Spanish Civil War.