Shelby joined WCCO-TV in 1978 as a news reporter. After continued work as a reporter, Shelby began assuming anchor responsibilities in greater capacity, eventually assuming the primary anchor chair from Dave Moore. Shelby was the chief architect behind WCCO's "I-Team" segment, which spotlighted current issues, both local and on a larger world scale, with rigorous investigative journalism. After suffering a mild stroke in early 2004, Shelby returned to news reading duties by the end of that year. Shelby retired from television after his final WCCO-TV newscast on November 22, 2010.
In February 2006, Shelby began hosting a series of video essay segments entitled "In The Know" (later renamed "Good To Know"), during the station's 10:00 newscast. These segments sometimes touched on political, religious and other topics, usually with the same pointed journalistic style of Shelby's earlier "I-Team" efforts.
In recent years, Shelby undertook a dual responsibility of hosting an afternoon radio show on WCCO (AM) which ended at 6:00, immediately after which he anchored the TV newscast (also simulcast on radio). In June 2009, Monday Night Football sideline reporter Michele Tafoya took over the radio show, which Shelby still occasionally contributes to as a guest. Shelby's final radio show took place on December 11, 2009.
Shelby has played an active role in the preservation and maintenance of the Mississippi River. Through his WCCO-TV segment entitled "Project Energy", Shelby has investigated energy conservation, renewable energy, and alternative fuels. Shelby has also given his time as an on-air representative for a number of pledge drives on behalf of the local PBS station TPT (KTCA), as well as narrated the third installment of "Lost Twin Cities", a TPT produced documentary. He has recently appeared in America Unearthed (2013)
Known to many in the Minnesota community as a "jack-of-all-trades," Shelby has many hobbies, including, among other things, beekeeping. Shelby has been an enthusiastic fan of women's basketball.
His first book, The Season Never Ends: Wins, Losses, and the Wisdom of the Game, was published on August 30, 2011. It features a foreword by former University of Minnesota men's basketball head coach Tubby Smith and endorsements from NBA analyst Ahmad Rashād and author Will Weaver.
His eldest daughter, Ashley Shelby, is the author of Red River Rising: The Anatomy of a Flood and the Survival of an American City and South Pole Station: A Novel. Another daughter, Lacy Shelby, is the former Director of Green Infrastructure for the City of New York's Department of Transportation. She is currently Principal Urban Designer for the City of Minneapolis. His youngest daughter, Delta Larkey, is a Licensed Marriage and Family Therapist and co-owner of St. Paul-based Family Development Center.
Shelby, in his time on television, popularized the Pratt necktie knot, to the extent that it is sometimes referred to as the "Shelby Knot" or "Pratt-Shelby." The knot was created by Jerry Pratt, an employee of the US Chamber of Commerce, who taught it to Shelby in 1986. The knot was considered at the time to be "the first new knot for men in over 50 years" by the New York Times. It is speculated that the knot had been in use for a time, but the knot simply had not been documented until Don Shelby made it famous by the help of Jerry Pratt and the Minneapolis clothier Kingford Bavender. Kingford Bavender is considered to have coined the term the "Shelby" knot.
In honor of the history of the Shelby Knot and Don Shelby, a bespoke clothier company by the name of King Brothers Clothiers partnered with Mr. Shelby and launched the Shelby Knot Collection of ties in the spring of 2013. Together, Don Shelby and King Brothers Clothiers, selected the designs of the ties that reflected Don's tastes.