McDonald's launched “I'm Lovin' It” globally as a major brand slogan in 2003.
The campaign was developed by the advertising agency Heye & Partner and introduced across multiple markets. Its short, conversational wording was designed to work internationally, while translations and local executions varied by country.
The campaign is especially associated with a five-note musical motif and with recordings by Justin Timberlake. The slogan marked a shift toward a more contemporary, youth-oriented brand identity than some of McDonald's earlier advertising lines.
The phrase is not the same as the earlier “You Deserve a Break Today” campaign, which began in 1971. McDonald's has used many temporary and regional advertising lines, but “I'm Lovin' It” became the company's best-known global tagline of the modern era.