Hadleigh United F.C. are an English football club based in Hadleigh, Suffolk. The club are currently members of the Eastern Counties League Premier Division, and play at the Millfield.
The club was founded in 1892 and joined Division Three, Section A of the Suffolk & Ipswich League (SIL) in 1929. For 1930–31 the club was moved to Division Two, Section B, and the following season to Division Two, Section A. After finishing second in 1935–36, they were promoted to Division One. However, after finishing bottom in 1937–38, the club were relegated back to Division Two, Section A.
After World War II the club returned to the SIL, playing in Division Three. In 1954 they moved to their current ground, the Millfield., though they were not allowed to play there in 1964 due to an unsatisfactory pitch, and problems with stones. The club dropped out of the SIL during the 1964–65 season, but re-joined for the 1965–66 campaign.
In 1968–69 the club won the Suffolk Senior Cup, beating Westerfield 3–2 in the final. They won it again in 1971–72 with a 1–0 victory over ICI Paints. The following season the club won the SIL for the first time. The 1976–77 season saw the club win the double, finishing as champions and winning the first McNeil League Knock-Out Cup. They won the league for a third time in 1978–79. More league cups were won in 1980–81, 1981–82 and 1986–87, whilst the Suffolk Senior Cup was taken in 1982–83 with a 4–1 win over Cranes.
In 1991 the club joined Division One of the Eastern Counties League. They won the division in 1993–94 to earn promotion to the Premier Division. The same season, floodlights were erected at the ground. However, after finishing 22nd out of 23 in 1996–97, the club returned to Division One.
The club won the Suffolk Senior Cup for a fourth time in 2003–04. In 2008–09 they finished runners-up in Division One and were promoted back to the Premier Division. In 2013–14 the club won the Eastern Counties League title for the first time.