Sunnyvale is a town in Dallas County, Texas, United States and a wealthy, affluent suburb of Dallas. It is the easternmost city completely within Dallas County. The population was 5,130 at the 2010 census.
Sunnyvale is located at 32°48′13″N 96°34′11″W / 32.80361°N 96.56972°W / 32.80361; -96.56972 (32.803646, -96.569654).
According to the United States Census Bureau, the town has a total area of 16.8 square miles (43.4 km²), all of it land.