In 1903 Robert Barr invited him to endorse his soft drink Iron Brew, using Donald's image on the label with Donald proclaiming "I can recommend BARR's IRN BRU to all who wish to aspire to athletic fame, signed Donald Dinnie, All-round Champion Athlete of the World." Later in Donald's life he struggled financially, and in his 70s was still performing as a strongman in London. His act was to support a platform made from a large table while two Highlanders danced a "fling" on it. Eventually London authorities terminated his performing licence because of his advanced age. To help with his situation, a benefit concert was organised which provided Dinnie with a small annuity. Donald and his family lived in Glasgow, where they owned a fish and chip restaurant and tea-room in the Govan area. They then lived for two or three years in Newcastle, England, before finally settling in London. Dinnie died in London in 1916, aged 78 years. In the United States, "The New York Times" paid tribute in the paper's obituary column. In 2002, Donald Dinnie was inducted into the Scottish Sports Hall of Fame in Edinburgh. Donald's relative Gordon Dinnie accepted a cut glass trophy on Donald's behalf. Gordon Dinnie also owned an original astrakhan breastplate that carries 19 medals won by Donald Dinnie from 1860 to 1896. A carved statuette of Donald Dinnie, engraved with the words "Presented to Donald Dinnie, Champion Athlete In Appreciation of his Athletic Prowess, by his Scotch Friends, In Newcastle 1870", is in the Aberdeen Art Gallery along with many of Dinnie's medals. In 1860, Dinnie undertook a feat of strength that was to give birth to a long-lasting legacy. He carried two granite boulders with a combined weight of , now known as the Dinnie Stones, for a distance of more than , across the width of the Potarch Bridge. Each boulder had an iron ring fixed to it, to counterweight scaffolds from which workmen could repair the bridge, over the River Dee near Kincardine O'Neil. As of August 2018, 90 men and three women have managed to lift the stones, and six men (including Donald and later his father) have carried them the full distance. The stones are now displayed outside the Potarch Café and Restaurant, on the south bank of the river by the Potarch Bridge. Lifting the Dinnie Stones (locally also "Stanes" and "Steens") remains a perpetual challenge.