“I'm Lovin' It” replaced “You Deserve a Break Today” as McDonald's global campaign slogan in 2003.
The campaign marked a move toward a single internationally recognizable message. McDonald's launched it in Munich, Germany, in September 2003, and the slogan was adapted for use across many markets. Its informal wording was intended to sound conversational and to connect the brand with enjoyment rather than simply speed or convenience.
The campaign is strongly associated with the “ba da ba ba ba” musical mnemonic. Justin Timberlake appeared in the original English-language advertising campaign, while the music and slogan were used in a broader global rollout.
The slogan is sometimes confused with earlier McDonald's phrases such as “You Deserve a Break Today” or “We Love to See You Smile.” Those were separate campaigns from earlier periods. “I'm Lovin' It” became the company's longest-running global tagline.