Joe Mattes was born in Heidelberg, Germany and was raised in Waterloo Region. He obtained his Honours Bachelor of Arts degree at the University of Toronto (psychology and philosophy) in 1980, and subsequently obtained his Bachelor of Laws degree from Western University in 1983, and was called to the Ontario bar in 1985. Joe practiced law in Toronto and was a partner in a major Waterloo law firm prior to establishing Matteslaw.

Joe lives in Kitchener with his wife Nancy and their two daughters. In his spare time he enjoys travel, cooking, golf and hiking. Joe has had considerable involvement in the community over the years including as a director of the Heart and Stroke Foundation and Kiwanis Club of Waterloo North, as a trustee of the Waterloo County Law Association and as a volunteer with the United Way, Renison College, the Canadian Association of Gift Planners and the Chamber of Commerce.