As early as 1941 Yakovlev was considering means whereby he could wring the highest possible performance out of the basic Yak-1 design. As there was no immediate prospect of more power, and armament and equipment were already minimal, the only solution seemed to be to cut down the airframe, reduce weight and reduce drag. In the Yak-1M the wing was reduced in size, the oil cooler replaced by twin small coolers in the wing roots, the rear fuselage cut down and a simple clear-view canopy fitted, the coolant radiator duct redesigned and other detail changes made. The result was a fighter even more formidable in close combat than the Yak-1 and Yak-9 families, though it landed faster.
The production Yak-3 was further refined by a thick coat of hard-wearing wax polish, and after meeting the new fighter during the mighty Kursk battle in the summer of 1943 the Luftwaffe recognised it had met its match. Indeed by 1944 a general directive had gone out to Luftwaffe units on the Eastern Front to "avoid combat below 5,000 m with Yakovlev fighters lacking an oil cooler under the nose". To show what thje Yak-3 could do when bravely handled, despite its armament - which was trivial compared with that of the German fighters - on 14th July 1944 a force of 18 met 30 Luftwaffe fighters and destroyed 15 for the loss of one Yak-3. Small wonder that, offered all available Soviet, British or American fighters, the famed Normandie-Niemen Group changed from the Yak-9 to the Yak-3 and scored the last 99 of their 273 victories on these machines.

It was natural that the more powerful VK-107 engine should have been fitted to the Yak-3, though the designation was not changed. After prolonged trials in early 1944 the Soviet test centre judged the 107-engined craft to be 60-70 mph faster than either a Bf109G or an Fw190, but the re-engined aircraft was just too late to see action in World War II. As in the case of the Yak-1 and the Yak-9, there were various experimental conversions of the Yak-3: Yak-3/VK-107A: about 100 built, in operation 1945; Yak-3/VK-108: experimental and fastest Yak-3 aircraft with VK-108 engine, first flown 19 December 1944, demonstrated a maximum speed of 463 mph (745 km/h) at 19,685 ft (6,000 m); Yak-3T: anti-tank version built in small numbers with 37-mm N-37 cannon and two 20-mm B-20S cannon; Yak-3T-57: one-off Yak-3T with a 57-mm 0KB-16-57 cannon; Yak-3P: small quantity with three 20-mm B-20 cannon and two 0.5 in (12.7 mm) UBS machine-guns; Yak-3RD (or Yak-3D): experimental adaptation of series aircraft to take Glushko RD-1 rocket unit in tail; Yak-3V: high-altitude variant; Yak-3PD: flown in 1944 with supercharged VK-106 engine; intended to have pressurised cabin; Yak-3U: rebuilt aircraft with ASh-82FN radial engine and twin B-20 cannon - despite heavy engine overall weight, weighed less than standard Yak-3 and during series of test flights started on 12 May 1945 demonstrated a maximum speed of 441 mph (710 km/h) at 20,015 ft (6,100 m); Yak-3TK: VK-107A-powered version tested in 1945 with turbocharger; Yak-3UTI: developed as conversion trainer in late 1945 with ASh-21 radial engine, became eventually Yak-11. Total production of the Yak-3 was 4,848. These fighters may have been smaller and simpler than those of other nations in World War II but they served the Soviet Union well in its hour of great need. They conserved precious material, kept going under almost impossible airfield and maintenance conditions and consistenly out-performed their enemies.