From the basic design MB 200 came the improved private venture MB.210 series. One of the major design changes in this form was the relocation of the main wing appendages to a low-mounted position along the fuselage sides. Additionally, the MB.210 incorporated a retractable undercarriage during a period when many new designs still featured fixed undercarriages (sometimes housed in aerodynamic fairings). Power was 2 x Gnome-Rhone 14K series radial piston engines of 800 horsepower each. Bloch tested the aircraft in flight for the first time on November 23rd, 1934. Ultimately two prototypes were produced, the second fitted with Hispano-Suiza powerplants of 860 horsepower each. Only the second prototype aircraft featured the retractable undercarriage, the first sported fixed legs
Bloch managed to sell the idea of his improved MB.210 bomber to French aviation authorities which resulted in a procurement contract and formal adoption of the series in November of 1936. Serialmanufacture would be handled by a several French manufactures including Les Mureaux, Breguet, Hanriot, Potez and Renault.
In practice, the MB.210 proved lacking in key areas, primarily centering around its engines which were not only prone to overheating in prolonged use but also in delivering the required power output for military service. The French Air Force, therefore, grounded their MB.210 fleet until these issues could be resolved. Bloch returned with slightly modified mounts that sported Gnome-Rhone 14N series radial engines. These engines proved more reliable than the original offerings and allowed the MB.210 to reenter active service once more.
Serial production for the Armee de L'Air (French Air Force) totaled 257 aircraft.
It was its availability in numbers that led the MB.210 to still be in use by the time of the German invasion of France in June of 1940. The aircraft were pressed into combat service with both the French air force and navy and the MB.210 equiped twelve French bomber groups during the fighting. By this time, the bomber was a wholly obsolete design caught up in a major modern war and losses were appropriately expected. When daylight bombing endeavors spelled disaster for French air crews at the hands of well-trained and experienced German fighters, the bomber was switched over to night offensives which proved little more successful.
Regardless, due to the desperate French state, it was used in action up until the formal French surrender. Some elements were shifted to North Africa to continue their service careers.
In the aftermath of the French surrender and subsequent German occupation, the MB.210 was used in small numbers and for a short time by the Luftwaffe into 1942. Six captured examples were shipped to German-ally Bulgaria and operated by the Bulgarian Air Force for a time. Romania proved another Axis-aligned operator, receiving some 10 examples out of an initial order for 24 aircraft.

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