What McDonald's slogan, introduced in 2003, became the brand's global tagline?

“I'm Lovin' It” became McDonald's global tagline in 2003.

The campaign was launched internationally in September 2003 and used the phrase across advertising, packaging, restaurant materials, and promotional activity. Its informal first-person wording was designed to sound like a personal expression rather than a formal corporate claim.

The campaign is especially recognizable for its “ba da ba ba ba” audio mnemonic. Pusha T has said he helped write the jingle, while the campaign's music and advertising were developed through McDonald's agency and production partners. Justin Timberlake appeared in an early campaign film, helping attract broad popular attention.

McDonald's had used many earlier slogans, including “You Deserve a Break Today” and “We Love to See You Smile.” Those phrases belong to earlier campaign periods. “I'm Lovin' It” is the long-running global tagline associated with the modern McDonald's brand.