Saint-Martin-lès-Seyne (French pronunciation: [sɛ̃ maʁtɛ̃ lɛ sɛn], literally Saint-Martin near Seyne; Vivaro-Alpine: Sant Martin de Sèina) is a commune in the Alpes-de-Haute-Provence department in southeastern France. With 7 inhabitants (as of 2023), it is the second least populated commune in the department, after Majastres.