In the 2021 Census of Population conducted by Statistics Canada, Saint-Célestin had a population of 892 living in 382 of its 403 total private dwellings, a change of 7.3% from its 2016 population of 831. With a land area of 1.41 km2 (0.54 sq mi), it had a population density of 632.6/km2 (1,638.5/sq mi) in 2021.[4]
Louis Bourgeois (1856–1930), architect and designer of the Bahá'í House of Worship in Wilmette, Illinois, was born in Saint-Célestin-de-Nicolet, Quebec on March 19, 1856.