The Avia B.135 was the first monoplane fighter designed by this Czechoslovakian firm which intended it as a replacement for the venerable B.534 biplane. This new fighter (originally designated as the B.35) had wooden elliptical wings and a welded steel tube fuselage structure covered by light alloys and fabric giving it a modern look which was complemented by a retractable undercarriage. Incredibly enough despite the German occupation, development continued albeit with a new designation and was immediately shown interest by a Bulgarian military mission which intended to license-produce it at home. In the event, none of this happened and only a dozen production aircraft entered service; they were assigned to that nation's Fighter Pilot School but some were used in combat (alongside older B.534s) against USAAF bombers on their way to the Ploesti airfields.

The first B.35 prototype had its maiden flight on 28 September 1938. The design was redesignated as the B.135 after the German occupation and no variants were built. Planned Bulgarian-built versions were known as the DAR-11 Ljastuvska (Swallow) but none were actually built.