The first ascent of the mountain was made in 1887 by James J. McArthur of the Dominion Land Survey.

[1] The mountain was named in 1916 by Alexander MacKinnon Burgess for Lieutenant-Colonel John Stoughton Dennis (1820–1885), a Canadian surveyor who proposed the Dominion Land Survey system in 1869.

[3][4] The mountain's toponym was officially adopted in 1924 by the Geographical Names Board of Canada.

[2] Mount Dennis is composed of sedimentary rock laid down during the Precambrian to Jurassic periods.

Weather conditions during winter make Mount Dennis one of the premier places in the Rockies for ice climbing.