McDonald's introduced the “I'm Lovin' It” slogan worldwide in 2003.
The campaign was launched internationally as a unified brand platform, giving McDonald's a short, upbeat phrase that could work across advertising, packaging, and multiple languages. Its conversational wording was designed to sound like a personal reaction rather than a formal corporate claim.
The campaign is also associated with a musical theme featuring the “ba da ba ba ba” mnemonic. Justin Timberlake appeared in an early campaign advertisement, and the campaign's music became closely linked with the McDonald's brand.
The slogan is sometimes dated to 2002 because development and early campaign work occurred before the international launch. The standard branding milestone, however, is 2003, when McDonald's rolled out “I'm Lovin' It” worldwide.