The club was established in 1883 and moved to its current ground on Mundford Road in 1905. They played in the Norwich and District League until World War I, but due to the town's position on the Norfolk-Suffolk border, the club could enter cups in both counties, and in 1911 were victorious in the Suffolk Junior Cup final.
After the war they played in leagues in both Norfolk and Suffolk until becoming founder members of the Eastern Counties League in 1935. However, they finished bottom in both 1935–36 and 1936–37 and returned to the county leagues. In 1948 they won the Norfolk Senior Cup, and in 1954–55 were Norfolk & Suffolk League champions.
In 1963 the club rejoined the Eastern Counties League. However, they never finished higher than fifth, and were bottom in both 1983–84 and 1984–85. In 1989–90 the club finished as runners-up in the Premier Division. Although they won the Norfolk Senior Cup final the following season, in 1991–92 they were relegated to Division One after finishing bottom. Aside from a fourth-placed finish in 1995–96, they have not finished higher than 11th, and finished bottom in 1998–99 and 1999–2000.
The period of the early–mid 2000s saw Thetford scrapping at the wrong end of the table, until a much improved finish of 11th in the 2006–07 season. Since this year, the club have established themselves as a mid table club with finishes of 13th (2007–08) and 16th (2008–09).
The 2009–10 season saw Thetford improve further, collecting their highest points total for a number of years and finishing in 11th place.
In 2011–12 the club finished second and were promoted to the Premier Division.
Norfolk & Suffolk League
Suffolk Junior Cup
Norfolk Senior Cup
Winners 1947–48, 1990–91
Best FA Cup – performance: Second qualifying round (five times)
Best FA Vase performance: Fourth round, 1990–91
Attendance: 394 vs Diss Town, Norfolk Senior Cup, 1991