The Mirage IV is similar to Mirage fighters, with tailless delta wing and a single square-topped vertical fin. It has two SNECMA Atar turbojets in the rear fuselage, with air intakes on both sides of the fuselage, very similar to the Mirage III's souris ("mice"). It can reach high supersonic speeds: the aircraft is redlined at Mach 2.2 at altitude because of airframe temperature restrictions, although it is capable of higher speeds. Although the aircraft has 14,000 liters of internal fuel, its engines are quite thirsty, especially in afterburner.
The crew of two (pilot and navigator) are seated in tandem cockpits under separate canopies. A bombing/navigation radar is located under a radome in the fuselage under the intakes, aft of the cockpit. A refueling boom is built into the nose, an important part of Mirage IV operations.

The Mirage IV has two pylons under each wing, the inboard pylons normally used for large drop tanks of 2,500 liter (660 gallon) capacity. The outers carry ECM and chaff/flare dispenser pods to supplement the internal jamming and countermeasures systems: on current aircraft, typically a Barax NG jammer pod under the port wing and a Boz expendables dispenser under the starboard wing. No cannon armament was fitted. The early Mirage IVA had a fuselage recess under the engines for a single AN-11 or AN-22 nuclear weapon of 60 kiloton yield.

From 1972 onward, 12 aircraft were also equipped to carry the CT52 reconnaissance pod in the bomb recess. The CT52 is available in either BA (Basse Altitude, low-level) or HA (Haute Altitude, high-altitude) versions with three or four long-range cameras. A third configuration is an infrared linescanner. None of the CT52 has any digital systems, relying on older 'wet' film cameras.

Later Mirage IVP aircraft could be fitted a single centreline pylon for the ASMP stand-off missile.

The Mirage IVA could theoretically carry up to six large conventional bombs at the cost of drop tanks and ECM pods, but such armament was rarely fitted in practice.