Claes Oldenburg was born in Stockholm, Sweden, the son of a Swedish diplomat stationed in New York. In 1936 his father was transferred to Chicago where Oldenburg grew up, attending the Latin School Of Chicago. He studied at Yale University from 1946 to 1950, then returned to Chicago where he took classes at the Art Institute of Chicago.

While further developing his craft, he worked as a reporter at the City News Bureau of Chicago. He also opened his own studio and, in 1953, became a naturalized citizen of the United States. His first recorded sales of artworks were at the 57th Street Art Fair in Chicago, where he sold 5 items for a total price of $25. He moved back to New York City in 1956. There he met a number of artists, including Jim Dine, Red Grooms, and Allan Kaprow, whose Happenings incorporated theatrical aspects and provided an alternative to the abstract expressionism that had come to dominate much of the art scene.

The most memorable aspects of Oldenburg's works are perhaps, the colossal sculptures that he has made in partnership with his late wife, Coosje van Bruggen. Sculptures, though quite large, often have interactive capabilities. One such interactive early sculpture was a soft sculpture of a tube of lipstick which would deflate unless a participant re-pumped air into it. In 1974, this sculpture, Lipstick (Ascending) on Caterpillar Tracks, was redesigned in a sturdier aluminum form, the giant lipstick being placed vertically atop tank treads. Originally installed in Beinecke Plaza at Yale, it now resides in the Morse College courtyard.

Many of Oldenburg's large-scale sculptures of mundane objects elicited public ridicule before being embraced as whimsical, insightful, and fun additions to public outdoor art. In the 1960s he became associated with the Pop Art movement and created many so-called happenings, which were performance art related productions of that time. The name he gave to his own productions was "Ray Gun Theater". His first wife -(1960—1970) Pat Muschinski who sewed many of his early soft sculptures, was a constant performer in his happenings. This brash, often humorous approach to art, was at great odds with the prevailing sensibility that, by its nature, art dealt with "profound" expressions or ideas. But Oldenburg's spirited art found first a niche then a great popularity that endures to this day.

His collaboration with Dutch/American writer and art historian Coosje van Bruggen dates from 1976. They were married in 1977.

In 1988, he and van Bruggen created the iconic Spoonbridge and Cherry sculpture for the Walker Art Center in Minneapolis, Minnesota that remains a staple of the Minneapolis Sculpture Garden as well as a classic image of the city.

In addition to freestanding projects, they occasionally contribute to architectural projects, most notably the former Chiat/Day advertising agency headquarters designed by Frank O. Gehry in the Venice district of Los Angeles, California...the main entrance is a pair of giant binoculars. The advertising agency DDB is the current tenant.

Another well known construction is the Free Stamp in downtown Cleveland, Ohio. This Free Stamp has an energetic cult following.

In 2000, he was awarded the National Medal of Arts.

In 2001, Oldenburg and van Bruggen created 'Dropped Cone', a huge inverted ice cream cone, on top of a shopping center in Cologne, Germany.

Claes Oldenburg supposedly has a work of art on the moon in the Moon Museum.

Claes Oldenburg is represented by The Pace Gallery in New York.

Image:Soft Bathtub.jpg|Soft Bathtub (Model)—Ghost Version by Claes Oldenburg 1966, acrylic and pencil on foam-filled canvas with wood, cord, and plaster. Hirshhorn Museum, Washington, DC.Image:Typewriter Eraser, Scale X.jpg|Typewriter Eraser, Scale X, by Claes Oldenburg and Coosje van Bruggen1999, painted stainless steel and FiberglasNational Gallery of Art, Washington, DC.File:FreeStamp.jpg|Free Stamp, outside City Hall in Cleveland, Ohio. Claes Oldenburg and Coosje van Bruggen, Painted steel-plate1985 (unveiled in 1991).Image:Crusoe umbrella.jpg|Crusoe Umbrella by Claes Oldenburg and Coosje van Bruggen, 1979, Cor-Ten steel painted with polyurethane enamel. Public art located in Nollen Plaza, Des Moines, Iowa.Image:City hall and clothespin.JPG|Clothespin by Claes Oldenburg, 1976. Public art displayed near Philadelphia City Hall in Philadelphia. The form of the sculpture is a visual pun referencing the tower of City Hall.Image:Middsbottle37.JPG|The Bottle of Notes sculpture in Middlesbrough UK.File:Claes Oldenburg, 1990.jpg|Pencil signature of Claes Oldenburg from 1990.Image:Dropped cone Cologne.jpg|Dropped Cone by Claes Oldenburg and Coosje van Bruggen, 2001. Situated on top of a shopping centre in the Neumarkt area of Cologne, Germany.