Harrington married Emily Hatten on March 10, 2007. They have known each other since high school but did not begin dating until after he had graduated from college. They have two sons, John "Jack" Patrick Harrington, born in 2009, and Emmet Harrington, born in 2012. Emily is a nurse practitioner, and Harrington spoke about them opening a medical clinic to serve the homeless in Portland, after he retired from football. One of Harrington's nicknames is "Piano Man," referring to the fact that he is an accomplished jazz pianist who has occasionally performed with artists such as Jason Mraz, Blues Traveler, and Third Eye Blind. On February 1, 2008, Harrington appeared as a guest chef on a special Super Bowl episode of "The Rachael Ray Show". Harrington is a distant cousin of professional golfer Pádraig Harrington and professional poker player Dan Harrington. Harrington's brother, Michael, played football at the University of Idaho, and was also a quarterback.