Although Walt Whitman had never visited Bon Echo, property owner Flora MacDonald Denison admired Whitman's work so much that she commissioned a piece of his poetry (from poem Song of Myself) to be chiseled into the face of the rock in foot-tall lettering, where it can still be seen today. The work was performed by two stonemasons and took all of the summer of 1919 to complete. After her death in 1921, the land and Inn was inherited by her son, Merrill Denison, a very successful writer and entrepreneur. He continued to operate the Inn until the beginning of the Great Depression in 1929. After that, the Inn was leased to the Leavens Brothers who operated it as a summer hotel, and other portions of the property were rented out for use as a boys' camp and other recreational purposes. In 1936, the Inn and many outbuildings were destroyed in a fire started by lightning striking the bake-house. The loss was not fully covered by insurance, and the Inn was never rebuilt. Merrill Denison continued to spend summers at Bon Echo, using it as a quiet location to write. In 1955, the province of Ontario passed legislation allowing them to accept donations of land to form provincial parks. Although he could have made a substantial profit dividing and selling sections of the property as building lots, Denison's interests in conservation led him to donate the land to the province for the purpose of forming a park in 1959.

Walt Whitman's longtime friend and biographer, Horace Traubel visited Bon Echo the Summer of 1919 for the Whitman centennial anniversary and the dedication of the rock to Whitman. Horace Traubel was very weak and near certain death. On 28 August Traubel, while sitting in a tower room at the Inn where he could look out on Old Walt, shouted that Whitman had just appeared above the granite cliff “in a golden glory.” “He reassured me, beckoned to me, and spoke to me. I heard his voice but did not understand all he said, only ‘Come on’” (qtd. in Denison 196). Traubel died at Bon Echo on 3 September and was buried in Harleigh Cemetery in Camden, close to Whitman’s tomb.