In March 1939, the plant began manufacturing its first aircraft — PZL.37 Łoś bombers, assembled from components delivered from the PZL WP-1 factory in Warsaw.

At first, it undertook aircraft repair works, and produced mostly non-aviation items, such as bus bodies, scales, etc.

The most numerous aircraft built in Mielec was the licensed Soviet Antonov An-2 utility biplane, produced from 1960 in different variants.

[2] From 1984, PZL Mielec became an exclusive producer of the Soviet Antonov An-28 STOL transport airrcaft, of which 180 were built.

On the other hand, the factory started cooperation with American firms, and the result was the very successful agricultural aircraft M-18 Dromader, first flown in 1976, and produced and developed until now (as of 2012).

WSK-Mielec also started production of the PZL M-20 Mewa utility aircraft (licensed Piper PA-34 Seneca), but a small number was built only.

Partly based on the M-20, the factory developed a successful light trainer PZL M-26 Iskierka of 1988; however, only seven were built.

The factory produced also non-aviation items, like fire engines (1948), refrigerators (1954–1966), Mikrus MR-300 microcar (1956–1960, 1728 built), refrigerator car bodies (1962–1974), TV broadcast cars (from 1965), fuel injection equipment (from 1964), Leyland-licence diesel engines (from 1967), Melex electric utility vehicles and golf carts (from 1970, mostly for export to the USA, later separated as own brand).

In 1993, a division Wytwórnia Aparatury Wtryskowej "PZL Mielec" (Fuel Injection Equipment Factory "PZL–Mielec") was separated as a limited liability company.

[2] After a fall of export to Eastern Bloc countries, production volume decreased, and there remained 1200-1400 workers.

[2] The circumstances of this transaction and its aftermath were heavily criticized by the Polish military press, suggesting that the price was very low (56.1 million PLN), due to pro-American lobbying.