Kathy Ireland was born Kathleen Marie Ireland in Santa Barbara, California, daughter of John Ireland, a labor union organizer, and Barbara. At 17, she was discovered by an agent for Elite Model Management, and by the time she graduated high school, she was working steadily as a model.

Starting with 1984, Ireland was featured in the annual Swimsuit Issue before her final appearance in 1996. In addition to her long tenure within the pages, Ireland appeared on the cover of the annual issue 3 times, a feat tied by Christie Brinkleyand Cheryl Tiegsand surpassed only by Elle Macpherson Ireland was the cover model for the first time on the 25th Anniversary Swimsuit Edition, which became SI's best selling to date. She returned to the cover in 1992, and in 1994. In her third appearance, she was accompanied by Rachel Hunterand Elle Macpherson notably, both Hunter and Ireland were pregnant at the time.

Ireland branched out from modeling into a small number of television and movie acting appearances. Her first movie, 1988's Alien from L.A., was later skewered during the fifth season of Mystery Science Theater 3000. Ireland also appeared in Melrose Place, Side Out, Mr. Destiny, Loaded Weapon 1, Once Upon A Christmas,Twice Upon A Christmas, and Necessary Roughness.

In 1993, Ireland dipped her toe in the waters of brand marketing when she put her name on a line of socks. Kmart took a chance on them and after they proved a best-seller, the retailer offered Ireland her own clothing line. Ireland then founded Kathy Ireland Worldwide (KIWW), a brand product marketing company in which she holds a majority stake. By 2004, Ireland was marketing products from 16 manufacturers, with Standard Furniture products representing about half the company's sales. Ireland's long-term exclusive contract with the Kmart Corporation lasted until 2003, after which she began adding thousands of independent mid-tier retail stores to her distribution chain. By 2005, KIWW products were sold at over 50,000 locations in 15 countries, generating an estimated $1.4 billion in retail sales. Ireland's annual take is thought to be around $10 million, which has prompted Forbes to name her the "prototype for model-turned-mogul" in an article about the trend of ‘modelpreneurs’.

Since 1994, Ireland has published several fitness videos. In 2004, she authored Powerful Inspirations: Eight Lessons that Will Change Your Life, published by Random House. In the book, Ireland uses the Bible and her Christian faith to highlight her life story and beliefs.