The Dominican Republic encompasses approximately two-thirds of Hispaniola, the second largest island in the Greater Antilles. It is situated with the Atlantic Ocean to the north and the Caribbean Sea to the south. The country shares the island with Haiti, dividing it roughly in a 2:1 ratio, and the border between the two countries stretches for 234 miles (376 km). To the north and northwest lie The Bahamas and the Turks and Caicos Islands, while the US Commonwealth of Puerto Rico is located to the west across the Mona Passage. The reported area of the Dominican Republic varies between 48,442 km2 (18,704 sq mi) and 48,730 km2 (18,815 sq mi), making it the second largest country in the Antilles after Cuba.

The Dominican Republic includes numerous small offshore islands and cays within its territory. The two largest islands near the shore are Saona, located in the southeast, and Beata, situated in the southwest. Other smaller islands include Cayos Siete Hermanos, Isla Cabra, Cayo Jackson, Cayo Limón, Cayo Levantado, Cayo la Bocaina, Catalanita, Cayo Pisaje, and Isla Alto Velo. Further to the north, at distances ranging from 100 to 200 kilometers (62 to 124 miles), are three expansive submerged banks: Navidad Bank, Silver Bank, and Mouchoir Bank. Geographically, these banks represent a southeast continuation of the Bahamas and have been officially claimed by the Dominican Republic.