Aircraft development was ordered by the Polish Air Force, but no prototypes were built.
Tests performed by Aerodynamic Institute of Warsaw University of Technology showed that the maximum speed of the LWS-7 could be estimated at 420–425 km/h - about 60 km/h more than the LWS-3 Mewa.
Complete technical drawings were prepared in Summer 1939 (still not confirmed) and the first prototype was planned to be built in Autumn 1939.
Drawings of LWS-7 were evacuated in September 1939 to the Polish embassy in Romania by the LWS director Aleksander Sipowicz.
Many publications claim that they were handed over to Bulgarians, but it is not clear (possibly, it concerned the LWS-3B plans, in fact).