The Mexican Navy (Armada de México or SEMAR) is the naval branch of the Mexican military responsible for conducting naval operations. Its stated mission is "to use the naval force of the federation for the exterior defense, and to help with internal order". The Navy consists of about 56,000 men and women plus reserves, over 189 ships, and about 130 aircraft. The Navy attempts to maintain a constant modernization program in order to upgrade its response capability.

Given Mexico's large area of water (3,149,920 km²) and extensive coastline (11,122 km), the navy's duties are of great importance. Perhaps its most important on-going missions are the war on drugs and protecting PEMEX's oil wells in Campeche in the Gulf of Mexico. Another important task of the Mexican Navy is to help people in hurricane relief operations and other natural disasters.

The Mexican Navy has its origins in the creation of the Ministry of War in 1821. From that year until 1939 it existed jointly with the Army in the organic ministry. Since its declaration of independence from Spain in September 1810, through the mid decades of the 19th century, Mexico found itself in a constant state of war, mostly against Spain which had not recognized its independence. Therefore its priority was to purchase its first fleet from the U.S.A. in order to displace the last remaining Spanish forces from its coasts.