The Botha was developed during the mid 1930s in response to Air Ministry Specification M.15/35, and was ordered straight off the drawing board alongside the competing Bristol Beaufort.

On 28 December 1938, the first production aircraft made the type's maiden flight; almost exactly one year later, it entered service with the RAF.

During September 1935, the British Air Ministry issued specification M.15/35, which called for a new reconnaissance/torpedo bomber to reequip RAF Coastal Command.

[1] Both of the proposed aircraft were originally intended to be powered by the Bristol Perseus radial engine, capable of producing 850 hp (634 kW).

[1] A consequence of the weight increase was that both designs suddenly required more power to be able to achieve their envisioned performance; however, while the Taurus, capable of producing up to 1,130 hp (840 kW), was provided for the Beaufort, the Botha only received the Perseus X, capable of up to 880 hp (660 kW), due to limited supplies of the Taurus engine.

Immediately upon receipt of the order, Blackburn set about establishing two production lines for the Botha at its main factory at Brough and its new facility in Dumbarton, Scotland; additional component manufacturing was performed at the Olympia works in Leeds.

[4] On 25 March 1939 it was delivered to RAF Martlesham Heath for performance and handling trials by the Aeroplane and Armament Experimental Establishment (A&AEE).

[7] In basic configuration, the Blackburn Botha was a twin-engined cantilever monoplane; the high-mounted wing was a deliberate design decision, intended to provide the best possible downward view for its crew.

The navigator and wireless operator's positions were within a separate central cabin reached via an entrance door with a built-in stepladder on the starboard side of the fuselage.

The final crew member, the gunner, was positioned to the rear of the wing in an egg-shaped power-assisted turret on the upper fuselage.

[4] As built, the Botha I was powered by a pair of Bristol Perseus X radial engines, each driving a de Havilland Type 5/11 Hydromatic three-bladed constant-speed propeller.

[11] Service testing of the Botha was marred by a series of accidents, although no common cause was ever discovered according to the aviation author Aubrey Joseph Jackson; nor did he consider the loss rate to be excessive for the era.

However, the Air Staff decided to withdraw the Botha from frontline service and transfer the surviving aircraft to secondary duties.