Guaynabo (Spanish pronunciation: [ɡwaiˈnaβo]; is a municipality in the northern part of Puerto Rico, located in the northern coast of the island, north of Aguas Buenas; south of Cataño; east of Bayamón; and west of San Juan. Guaynabo is spread over 9 wards and Guaynabo Pueblo (the downtown area and the administrative center of the suburb).  Guaynabo is considered, along with its neighbors - San Juan and the municipalities of Bayamón, Carolina, Cataño, Toa Alta, Canovanas, Caguas, Toa Baja, and Trujillo Alto - to be part of the Área Metropolitana (Metropolitan Area) of San Juan (the largest MSA in Puerto Rico; many Puerto Ricans erroneously consider it^{[citation needed]}the only metropolitan area in the Commonwealth). It is also part of the larger San Juan-Caguas-Fajardo Combined Statistical Area. The municipio has a land area of 70.26 km² (27.13 sq mi) and a population of 100,053 as of the 2000 census.

 EconomyLong considered to be just a mostly rural, drive-by town for drivers who were going from San Juan to the western part of Puerto Rico, Guaynabo went through a large economic revitalization in the 1950s and 1960s. As a consequence, parts of the city have also served as a San Juan suburb preferred by upper-middle and high-income families. Today, Guaynabo has the highest per capita income in Puerto Rico. The neighborhoods of Garden Hills, Torrimar, San Patricio and Tintillo are among the upper class neighborhoods located in Guaynabo that were built in the 1950s and 1960s, with the notable exception of Villa Caparra and Suchville, San Juan's first wealthy suburbs, which were built in the 1920s. Residential construction continued between the 1970s and 1990s, where hundreds of new upper middle class developments were built: Parkville, Mallorca, Tierra Alta, Villas Reales, Ext. Villa Caparra, Mansiones de Guaynabo, Mansiones Reales, and Palmas Reales, among many others.

As a result of the proliferation of upper middle class and wealthy neighborhoods, several prominent private schools were founded in Guaynabo, including Academia San José, Colegio Marista, Colegio Adianez, and which mainly instruct in Spanish, although most private schools extensively cover English to levels comparable to those of the mainland; and Parkville School, American Military Academy, Baldwin School, in the Guaynabo-Bayamón border, and Wesleyan Academy, which mainly instruct in English. The first modern shopping mall built in the Caribbean and Latin America, San Patricio Plaza, was built in Guaynabo in 1963, in the San Patricio sector next to Villa Caparra.

Guaynabo's skyline is filled with over a hundred high-rise buildings. Most are residential condominiums, but the buildings also include various major headquarters for banks and other businesses.