Knottenbelt grew up in Kota Radja and later in his youth in Bussum. He was a member of tennis club Het Spieghel. In 1927 he became Dutch junior champion. In 1931 and 1932 he became Dutch champion in the men's doubles together with Ody Koopman. In 1931 (with Els Belzer) and in 1936 (with Truid Terwindt) Knottenbelt became national champion in the mixed doubles. In singles he was less successful, partly due to the hegemony of Henk Timmer.
In 1931, 1932, 1934 and 1936, Knottenbelt took part in the Wimbledon tournament. In 1931 he reached the second round in the singles and men's doubles (with Ody Koopman). In the mixed doubles he reached the fourth round with Madzy Rollin Couquerque in 1932 and the third round with the British Davinia Townsend in 1934. Joop Knottenbelt played two matches with the Netherlands in the 1934 Davis Cup. Against Monaco (4-1 win) he won both singles games and against Sweden (3-2 win) he lost twice.
In 1937 he left for the Dutch East Indies together with fellow tennis player and future brother-in-law Dick Rinkel, ending his sports career. In India, he entered the service of the Aceh Trading Company in Kota Radja, the place where he grew up.  Back in the Netherlands, he went to work for Philips. From the fifties to 1970 Knottenbelt lived in Curaçao, where he was director of Philips Antillana NV. 
His brother and both sisters were also active on the tennis court. Anton Knottenbelt was a talented tennis player, but died in an accident in 1932 at the age of 19.  Truus Knottenbelt was active at national level until her marriage in 1938 to Dick Rinkel. Anna Koopmans-Knottenbelt was Dutch champion in the mixed doubles in 1950.
J.H. Knottenbelt died in 1998 at the age of 87 in Spain, where he lived at the time. 
Your email address will not be published. Required fields are marked *