Hainaut (/eɪˈnoʊ/ ay-NOH, also US: /heɪˈ-, ɛˈ-/ hay-, eh-, UK: /ˈ(h)eɪnoʊ/ (H)AY-noh;[5][6][7] French: [ɛno]; Dutch: Henegouwen [ˈɦeːnəɣʌu.ə(n)] ⓘ; Walloon: Hinnot; Picard: Hénau), historically also known as Heynault in English, is the westernmost province of Wallonia, the French-speaking region of Belgium.

To its south lies the French department of Nord, while within Belgium it borders (clockwise from the north) on the Flemish provinces of West Flanders, East Flanders, Flemish Brabant and the Walloon provinces of Walloon Brabant and Namur.

The village of L'Escaillère in the utmost southeastern corner, at an altitude of 365 metres, is the highest point of the province.

Also well-known is the Pays des Collines (English: "Hill Country"), a low hilly area forming one natural region with the Flemish Ardennes in the East Flanders province.

The gross domestic product (GDP) of the province was €34.2 billion in 2018, accounting for 7.4% of Belgium's economic output.