Monchaux or de Monchaux is a surname. Notable people with the surname include:
Cathy de Monchaux (born 1960), British sculptor Henriette Delamarre de Monchaux (1854–1911), French naturalist and geologist Jan Monchaux (born 1978), French and German engineer John de Monchaux (1936–2018), Australian-American architect, city planner, and educator Nicholas de Monchaux (born 1973), designer and author Paul de Monchaux (born 1934), Canadian sculptor