It is bordered to the west by southern Greenland, to the north by Iceland and the Denmark Strait, to the east by the Reykjanes Ridge (a northern part of the Mid-Atlantic Ridge), and to the south by open waters of the North Atlantic.

To the southwest, it reaches to Cape Farvel, the southern tip of Greenland, and meets the Labrador Sea at this point.

South of this point is the open North Atlantic Ocean.

The sea floor of the Irminger Sea is largely part of the Irminger Basin, a northeastern continuation of the maximally 4,600 m (15,100 ft) deep Labrador Basin, which on the east is bordered by the Reykjanes Ridge.

This delineation is oceanographic only and does not represent any official borders.