A private venture by Heinkel to test radical ideas by the Günter brothers, the He 119 was originally intended to act as an unarmed reconnaissance bomber capable of eluding all fighters due to its high performance.

A prominent feature of the aircraft was the streamlined fuselage, which had an extensively glazed cockpit immediately behind the propeller.

Two of the three-man crew sat one each side of a driveshaft, which ran aft to a coupled pair of Daimler-Benz DB 601 engines mounted above the wing center-section, mounted together within a common mount (the starboard component engine having a "mirror-image" centrifugal supercharger) with a common gear reduction unit fitted to the front ends of each engine, forming a drive unit known as the DB 606.

On 22 November 1937, the fourth prototype (V4) made a world class-record flight in which it recorded an airspeed of 505 km/h (314 mph), with a payload of 1,000 kg (2,205 lb), over a distance of 1,000 km (621 mi).

These four aircraft were three-seaters with a defensive armament of one 7.92 mm (0.312 in) MG 15 machine gun in a dorsal position, V7 and V8 having provision for a normal bombload of three 250 kg (551 lb) bombs or maximum bombload of 1,000 kg (2,205 lb).