Designed as a dedicated reconnaissance aircraft to replace the RF-86F in the Armee de l’Air, the aircraft eventually equipped 3 squadrons 3/33, 2/33 and 1/33.

The main difference between this aircraft and the fighter version involved the removal of the Cyrano radar from the nose and replacing it with up to 5 Omera Type 31 optical cameras configured for either low, medium or high altitude photography. The IIIRD version was equipped with a chin bulge for doppler radar, a gyro sight and a modified nose pack containing Omera Type 40 and 33 cameras. The 5R version was a similar conversion of the Mirage 5. Since 1071 the SAT Cyclope 160 A5 Infra Red Linescan was often installed in the nose.

Operators include: France (IIIR and RD), South Africa (IIIRZ, R2Z), Pakistan (IIIRP), Switzerland (IIIRS), Abu Dhabi, Belgium, Colombia, Egypt, and Libya (5R).

The use by the Israeli Air Force (IAF) of their version of the Mirage III, the Mirage IIICJ, during the Six Day War did more for sales of a particular aircraft than any other event in military aviation. When the order for 76 aircraft was placed by the IAF, it was sub-divided into 70 Mirage IIICJs, 2 reconnaissance Mirage IIIRJs and 4 Mirage IIIBJ two-seat trainers. However, before the pre-emptive strike of 5 Jun 67, the IAF had already used the capability of their 2 reconnaissance Mirage IIIRJs (serial numbers 98 and 99) to conduct reconnaissance sorties against the surrounding Arab states. Israeli industry had developed a removable nose section for the two Mirage IIIRJs which could house a variety of cameras. The two Mirage IIIRJs gave many years of valuable service before they were eventually replaced by the McDonnell Douglas RF-4E.