Lago Vista is located on the north shore of Lake Travis, 20 miles (32 km) northwest of Austin.
According to the United States Census Bureau, the city has a total area of 15.2 square miles (39.4 km2), of which, 14.6 square miles (37.8 km2) of it is land and 0.6 square miles (1.6 km2) of it (3.95%) is water.