During his fifty year career, Carl Ahrens was frequently represented at exhibitions for the Ontario Society of Artists, the Royal Canadian Academy, and the Art Association of Montreal. His work was at the Canadian National Exhibition in 1891, 1895, 1896, 1923, and 1930.
Ahrens' painting Cradled in the Net was exhibited at the World's Columbian Exhibition in Chicago in 1893.
His first one-artist exhibition took place at Roycroft in East Aurora, New York in 1900. Three of his California mission paintings were exhibited at the Smithsonian in 1909.
In July 1908 Ahrens met his future patron, Major-General Malcolm Smith Mercer, at a one artist show in Toronto. The Mercer Collection was exhibited to the public in October of 1911 and received international acclaim.
The Roberts Art Gallery in Toronto, Ontario, hosted an Ahrens exhibit in 1917.
The first one-artist show to include Ahrens' prints took place in 1933 at Cunningham's Studio in Hamilton, Ontario.
In 1935, after the death of both Mercer and his brother, certain works from the Mercer Collection were again exhibited and sold.
There have been three one-artist exhibitions since Carl Ahrens passed away. The Memorial Exhibition took place at Mellors Galleries in Toronto in 1937. The Kitchener/Waterloo Art Gallery held an exhibition of Ahrens' prints in 1984. The most recent exhibition in the United States occurred in 1995, at Meibohm Fine Arts near the Roycroft campus in East Aurora, NY.
The Mercer Collection was a group of 31 oils that Major-General Malcolm S. Mercer commissioned Carl Ahrens to paint between the years 1908-1911. The collection was exhibited to the public in October of 1911 in the Public Reference Library (Toronto) and generated a lot of press.
Memorial Exhibition of Selected Works by Carl Ahrens - Mellors Galleries - 759 Yonge Street, Toronto - February 1937
Exhibited paintings: The Ridges, Pasture Land, The Wooded Lane, The Wooded Slope, The Village, The Woods, The Forest Way, The Uplands, Night, Autumn, Moving Shadows, Upland Road, Frosty Morning, The Mill, The Morning Sun, The Ford, The Evening Sun
Carl Ahrens as Printmaker- Kitchener-Waterloo Art Gallery -- Kitchener, Ontario 7 June - 15 July 1984
Exhibition featured all known prints
Meibohm Fine Arts in East Aurora, NY - 20 May - 1 July 1995
Exhibited works included paintings, prints, pastels, and sketches from the estate of John Noble Mackendrick. Mackendrick was a close friend of Ahrens during the years that the family lived in Galt, Ontario.