Mary Kay Inc. is an American privately owned multi-level marketing company. Mary Kay was the sixth largest network marketing company in the world in 2018, with a wholesale volume of US$3.25 billion. Mary Kay is based in Addison, Texas, outside Dallas.

Mary Kay sells cosmetics through a multi-level marketing model. Mary Kay distributors (called beauty consultants) can potentially make income by directly selling to people in their community, and also receive a commission on wholesale purchases made by people they recruit into the distribution network. Mary Kay distributors must purchase a $100 starter kit to qualify. As a private company, Mary Kay releases few details about the average income of its sellers. In 2005, Mary Kay reported that its wholesale worldwide sales exceeded US$2.2 billion. In 2010, worldwide wholesale figures were reported at US$2.5 billion. In 2015, worldwide wholesale figures were reported at US$3.7 billion. In 2018, worldwide wholesale figures were reported at US$3.25 billion. None of these figures take into account product returns.