Princeton is a city in Collin County, Texas, United States. As of the 2010 census it had a population of 6,807, with an increase to 17,027 in 2020.

Collin County is located in the U.S. state of Texas. It is part of the Dallas-Fort Worth-Arlington metropolitan statistical area, and a small portion of the city of Dallas is in the county. At the 2020 United States census, the county's population is 1,064,465, making it the sixth-most populous county in Texas and the 43rd-largest county by population in the United States. Its county seat is McKinney.