Fairfield Lake State Park, State park in Freestone County, United States.

Fairfield Lake State Park covered 1,460 acres on the shore of Fairfield Lake, a reservoir on Big Brown Creek in Freestone County, Texas. The park had facilities for picnicking, hiking, biking, fishing, kayaking, paddle boarding, swimming, boating, tubing, jet skiing, water skiing, wildlife observation, horseback trails, wildlife photography, group events, RV camping, tent camping, and primitive camping.

The park land was acquired in 1954 through a Department of the Army lease, later extended to 2004. Texas Power and Light Company dammed Big Brown Creek in 1969 to create a cooling reservoir for its power plant, and the park opened to the public in 1976. TPWD leased the site from Vistra for 50 years at no cost until the 2023 closure.

Chancellor Union Cemetery, on park land, holds graves of early area settlers, including Civil War, WWI and WWII veterans. The cemetery is still in active use but is not maintained by the park. In the Springfield camp loop, an old well remains from the Hill family homestead.

The park offers more than a hundred camping spots with vehicle pads, grilling areas, and fire rings for guests. Restroom facilities and showers are available to make your stay comfortable.

The 1,460-acre park was leased from Vistra at no cost for 50 years. In 2023 Vistra sold 5,000 acres, including the park, to Todd Interests after TPWD declined to buy the whole tract. TPWD later dropped its eminent domain case, ending state park status.