Union Valley is a city in Hunt County, Texas, United States. The city voted to incorporate in an election held on November 6, 2007. A total of 90 votes were cast (out of 173 registered voters), 75 (83.3%) in favor of incorporation and 15 (16.7%) against. According to the Union Valley incorporation committee, the city has about 78 households. The U.S. Census Bureau 2010 Census placed the population at 307.