Koninklijke Tesamen Hogerop Diest is a Belgian association football club from the town of Diest, Vlaams Brabant. It played two spells in the first division: from 1961–62 to 1964–65 and from 1970–71 to 1974–75, finishing 7th in 1964.
The club was founded in 1909 as Hooger Op Diest Football Club and registered to the Belgian Football Association the same year to receive the matricule n°41. In 1948 it merged with Standaard Athletiek Diest to become F.C. Diest. Seven years later it added Koninklijke to become K.F.C. Diest.
The club first reached the second division in 1957. It won this competition in 1961 and subsequently played at the highest level for the following years. In 1965 it was back at the second level and it won the competition again in 1970. In 1987–88 it played in the third division but promoted thereafter. On that occasion, K.F.C. Diest merged with F.C. Assent to become K. Tesamen Hogerop Diest. It was relegated again to the third division in 1996 and then the club decayed. It now plays in the highest regional league of Brabant, as of 2005.