McDonald's introduced the slogan “I'm lovin' it” in 2003.
The campaign marked a major shift toward a shorter, more conversational brand message. Its lowercase styling and pop-oriented presentation were designed to connect McDonald's with a younger, international audience while keeping the wording easy to recognize across markets.
The campaign is often associated with Justin Timberlake because he appeared in early advertising and recorded a related song. However, the slogan itself is McDonald's brand line, not the title of a McDonald's product. The campaign also used the “ba da ba ba ba” mnemonic in its advertising.
Earlier McDonald's lines included “You Deserve a Break Today,” which ran in the 1970s. “I'm lovin' it” replaced that earlier era's style with a global campaign that remains closely identified with McDonald's.