McDonald's launched “I'm Lovin' It” globally in 2003 as the central phrase of a new branding campaign.
The campaign began in Munich, Germany, in September 2003, and McDonald's expanded it internationally soon afterward. It was created with advertising agencies associated with the company and used a consistent English-language phrase across many markets. The wording was designed to sound conversational and to emphasize an immediate emotional response rather than a technical product claim.
The campaign became closely linked with a musical track performed by Justin Timberlake. The “ba da ba ba ba” vocal hook became one of the most recognizable audio signatures in modern fast-food advertising. McDonald's continued adapting the campaign for local languages and markets while keeping the English phrase as a global brand marker.
Earlier McDonald's slogans included “You Deserve a Break Today” and “We Love to See You Smile.” Those lines belong to earlier campaigns, so the 2003 launch is the decisive clue for identifying “I'm Lovin' It.”