Knut Knudsen (born 12 October 1950) is a retired Norwegian road and track cyclist. As an amateur he competed on track in the individual 4000 m pursuit at the 1968 and 1972 Olympics and 1973 World Champsionships, and won the event in 1972 and 1973. At the 1972 Olympics he also placed fifth in the 100 km team time trial on the road. He won the Norwegian National Road Race Championships in 1972 and 1973.
Between 1966 and 1973 Knudsen won 11 Norwegian championships. In 1974 he turned professional and cycled in Italy until 1981. He won six stages of the Giro d'Italia and wore the pink leader jersey in this major tour. Knudsen won Tirreno–Adriatico in 1979. He was chosen the world's best time trial cyclist by two biggest sporting magazines from 1979 to 1981. In total he won 49 professional races.