McKenna was the brains behind the original ad campaign for the launch of Apple in 1984 . He began working with the company in 1976. In that year, Steve Jobs and Steve Wozniak approached him and asked for help in launching what was to be the world's first personal computer. He agreed, because he "liked Apple's vision". A 2012 article quotes McKenna as saying, "when a young Steve Jobs needed a marketing expert, he called Intel to ask who made their sharp-looking ads and was told Regis McKenna." Not only did he write their first business plan, he also designed the Apple logo and put together their advertising campaigns. McKenna was the mastermind behind Apple's famous 1984 television commercial.
In addition to marketing consultancy, McKenna also owned an advertising agency and a public relations company which he sold to Jay Chiat and is today known as TBWA/ Chiat Day which is part of the one of the largest advertising networks in the world. McKenna said that the biggest mistake of his career was turning down an offer of 20% of Apple stock in lieu of payment for his services. "I was looking at my cash flow and that's one of the reasons why I turned down Apple's offer." His letter turning down the offer is on display at Apple's headquarters.