IDEO is an international design and innovation consultancy founded in Palo Alto, California, United States with other locations in San Francisco, Chicago, New York, Boston, London, Munich, Shanghai, Singapore, Mumbai, Seoul, and Tokyo. The company helps design products, services, environments, and digital experiences. Additionally, the company has become increasingly involved in management consulting and organizational design.

IDEO was formed in 1991 by a merger of four established design firms: David Kelley Design (founded by Stanford University professor David Kelley), London-based Moggridge Associates and San Francisco's ID Two (both founded by British-born Bill Moggridge), and Matrix Product Design (founded by Mike Nuttall). Office-furniture maker Steelcase owned a majority stake in the firm, but began divesting its shares through a five-year management buy-back program in 2007. The founders of the predecessor companies are still involved in the firm. The current CEO is Tim Brown.

The firm employs over 550 people in the disciplines of human factors, mechanical, electrical and software engineering, industrial design, interaction design, and communication design. IDEO has worked on thousands of projects for a large number of clients in the consumer food and beverage, retail, computer, medical, furniture, toy, office, and automotive industries. Notable examples are Apple's first mouse, Microsoft's second mouse, the Palm V PDA, and Steelcase's Leap chair. Major clients (as of 2004) included Procter & Gamble, PepsiCo, Microsoft, Eli Lilly, Ford, and Steelcase.

In 1999, the firm was the subject of the "Deep Dive" episode of ABC's Nightline; they redesigned a shopping cart in five days. In 2001, IDEO's general manager Tom Kelley wrote The Art of Innovation, and in 2005, The Ten Faces of Innovation (both co-written with Jon Littman). IDEO's current CEO Tim Brown published a book on design thinking called Change By Design (co-written with Barry Katz).

IDEO was featured in Gary Hustwit's 2009 design documentary Objectified.

IDEO has won more of the BusinessWeek/IDSA Industrial Design Excellence Awards than any other firm. IDEO has been ranked in the top 25 most innovative companies by BusinessWeek and does consulting work for the other 24 companies in the top 25.