Born in Øster Vrå Denmark, Kjærholm began as a cabinetmaker's apprentice with Gronbech in 1948, going on to the Danish School of Arts and Crafts in Copenhagen . in 1952. In 1953, he married Hanne Kjærholm who became a successful architect. He was very articulate and with his natural authority he started an outstanding career as an educator in the same year (1952) but continued to study with Prof. Erik Herløw and Prof. Palle Suenson. From the mid-1950s he worked for his friend Ejvind Kold Christiansen, an entrepreneur who, giving him tremendous artistic freedom, produced an extensive range of his furniture. His distinctive style is evident as early as 1952 in his PKO minimalist plywood series. The PK61 coffee table of '55 is a playfully irrational supporting frame visible through the glass top.
In 1958 he attracted international acclaim for his contributions to the 'Formes Scandinaves' exhibition in Paris and the award of the legendary 'Lunning Award', the same year for his PK22 chair. In both 1957 and 1960 he won the Grand Prize at the Milan Trennali. In 1959 he became assistant at the Royal Danish Academy of Fine Arts in Copenhagen and lecturer. In 1965 his PK24 Chaise Longue typified his mature style. Its simple flowing lines combine steel and woven cane. In 1967 he was awarded the Danish ID Prize for product design. He became head of the Institut for Design in 1973 and finally professor in 1976 until his death 4 years later.
Most of his furniture was initially produced by his friend E. Kold Christensen in Hellerup. Since 1982 a wide selection of those products have been produced by Republic of Fritz Hansen, a leading Danish furniture manufacturing firm. His designs are in the permanent collection of the Museum of Modern Art in New York, the Victoria and Albert Museum in London and other museum collections in Denmark, Norway, Sweden and Germany.
In typically Scandinavian fashion, most of Kjærholm’s contemporaries opted for wood as their primary furniture construction material. Kjærholm chose steel as his primary, but always combined it with other materials such as wood, leather, cane or marble. "Steel’s constructive potential is not the only thing that interests me; the refraction of light on its surface is an important part of my artistic work. I consider steel a material with the same artistic merit as wood and leather," he commented.
In 2004, Kjærholm's son established Kjærholm Productions to produce those items of his father's furniture that Fritz Hansen had discontinued production of in 2003. In 2008, Gregory R. Miller & Co. published the comprehensive and definitive reference work, The Furniture of Poul Kjærholm: Catalogue Raisonné, by Michael Sheridan.