The Prix Iris for Best Sound in a Documentary (French: Prix Iris du meilleur son film documentaire) is an annual film award, presented by Québec Cinéma as part of its Prix Iris awards program, to honour the year's best film sound in documentary films made within the Cinema of Quebec.
The award was presented for the first time at the 20th Quebec Cinema Awards in 2018.
Marie-Pierre Grenier and Jean Paul Vialard received the most nominations, four, with Vialard winning two consecutive awards in 2019 and 2020.