Duncan is most commonly associated with the Yo-yo, the commercial success and iconic status they enjoyed during the 20th century in the United States and the world being largely the result of his marketing efforts.

The name Yo-Yo was a trademark of his company from 1930 until 1965, when the case Donald F. Duncan, Inc. v. Royal Tops Mfg.

1965) resulted in a federal court of appeals ruling in favor of the Royal Tops Company, asserting that the trademark had become a part of common speech.

[1] Duncan, who was born in Kansas City, Missouri, founded other companies, including the Good Humor mobile frozen treats franchise and a parking meter manufacturing company.

[2][3] Most notable among the innovations credited to Duncan is the concept of the premium incentive, a marketing tactic wherein the consumer is encouraged to collect proofs of purchase and redeem them for rewards, such as small toys or discount coupons.