Guerrero (Spanish pronunciation: [ɡeˈreɾo]), officially the Free and Sovereign State of Guerrero (Spanish: Estado Libre y Soberano de Guerrero), is one of the 32 states that comprise the 32 Federal Entities of Mexico, located in Southwestern Mexico. It is divided in 81 municipalities. The state has a population of about 3.5 million people. It is bordered by the states of Michoacán to the north and west, the State of Mexico and Morelos to the north, Puebla to the northeast and Oaxaca to the east. In addition to the capital city, Chilpancingo and the largest city Acapulco, other cities in Guerrero include Petatlán, Ciudad Altamirano, Taxco, Iguala, Ixtapa, and Zihuatanejo. Today, it is home to a number of indigenous communities, including the Nahuas, Mixtecs, Tlapanecs, Amuzgos, and formerly Cuitlatecs. It is also home to communities of Afro-Mexicans in the Costa Chica region.

The state was named after Vicente Guerrero, one of the most prominent leaders in the Mexican War of Independence and the second President of Mexico. It is the only Mexican state named after a president. The modern entity did not exist until 1849, when it was carved out of territories from the states of Mexico, Puebla, and Michoacán.

Geographically, the state is mountainous and rugged with flat areas limited to small mesas and the Pacific coastline. This coastline has been important economically for the area, first as the port of Acapulco in colonial and post-Independence era and today for the tourist destinations of Acapulco, Zihuatanejo and Ixtapa. Tourism is the single most important economic factor of the state and Acapulco's tourism is important to the nation's economy as a whole. Agriculture and mining are also important to the state's economy, with production of crops like bananas, coffee, rice, corn, and sugarcane, as well as mined copper, sliver, and gold. However, other sources of employment are scarce in the state, which has caused its ranking as number one in the emigration of workers to the United States.