Mieres has a population of approximately 40,000 residents, with the majority being native Asturians. The city has experienced population fluctuations due to its industrial past, which attracted workers from other parts of Spain and abroad. Today, Mieres has a diverse population with a mix of families, young professionals, and retirees.
The city has a relatively older population due to the decline of its traditional industries, though in recent years, younger generations have been drawn to the area thanks to its growing university presence and renewed focus on tourism and services. This mix of age groups contributes to a vibrant and active community life.