Ungava Bay (French: baie d'Ungava, Inuktitut (syllabics/Roman) ᐅᖓᕙ ᑲᖏᖅᓗᒃ/ungava kangiqluk) is a large bay in northeastern Canada separating Nunavik (far northern Quebec) from Baffin Island. The bay is roughly oval-shaped, about 260 km (160 mi) at its widest point and about 320 km (200 mi) in length; it has an area of approximately 50,000 km² (19,000 sq mi). It is generally fairly shallow, under 150 m (490 ft), though at its border with the Atlantic Ocean depths of almost 300 m (980 ft) are reached.

There are a number of islands within Ungava Bay. The largest, Akpatok Island, and others north of 60°N are part of the territory of Nunavut, whilst smaller islands south of 60°N belong to Quebec.

Although it is quite close to the open Atlantic (separated only by Hudson Strait), Ungava Bay is generally considered part of the Arctic Ocean because the land surrounding it has an exceedingly cold climate. Due to the influence of the Labrador Current, summers are too cold for tree growth and all the land surrounding the bay is treeless tundra. Typically, temperatures in summer at Kuujjuaq about twenty kilometres up the Koksoak River are about 7 °C (45 °F), whilst winter temperatures are about −20 °C (−4 °F). Precipitation averages around 400–450 mm (16–18 in) per year, most of it falling in the summer.