Justin Timberlake appeared on the original English recording linked to McDonald's “I'm Lovin' It” campaign.
The campaign launched in 2003 and used a musical theme connected with Timberlake. His involvement helped give the advertising identity a contemporary pop-music profile, while the phrase itself became McDonald's global tagline.
The song-related material is sometimes treated as a conventional standalone pop release, but its best-known role was as part of a large commercial branding campaign. McDonald's adapted the campaign internationally, so not every market used identical music, performers, or language.
Timberlake's participation should not be confused with later artists who worked with McDonald's or with producers associated with the campaign. The key branding fact is that his vocal performance was connected to the original English-language version used to support the slogan.