Yakovlev OKB created 22 modifications of the Yak-9, of which 15 saw mass production. The most notable of these include: ;Yak-9 The first production version, with a
Klimov M-105PF engine with , 1 ×
ShVAK cannon with 120 rounds, and 1 ×
UBS machine gun with 200 rounds. ;Yak-9 (M-106) A prototype with the
Klimov M-106-1SK engine with . It did not advance to production because of problems with the engine. ;Yak-9T A Yak-9 armed with a
Nudelman-Suranov NS-37 cannon with 30 rounds instead of the ShVAK. The cockpit was moved back to compensate for the heavier nose. A problem corrected during prototype tests was poor quality control that led to multiple oil and coolant leaks from cannon
recoil. Recoil and a limited supply of ammunition required accurate aiming and two- or three-round bursts. The Yak-9T was widely used against enemy shipping on the
Black Sea and against tanks the cannon could penetrate up to armor from but was also successful against aircraft: a single cannon hit was usually sufficient to tear apart the target. Virage (constant altitude and speed turn) time was 18–19 seconds. 2748 were produced. ;Yak-9K A Yak-9T modified with a
NS-45 cannon with 29 rounds and a distinctive
muzzle brake to deal with the massive
recoil. Firing the cannon at speeds below caused a dramatic loss of control and tossed the pilot back and forth in the cockpit; however, accurate shooting was possible at higher speeds and in two- to three-round bursts. The recoil also caused numerous oil and coolant leaks. The heavy cannon decreased performance dramatically, especially at high altitudes, to the point that Yak-9Ks were relegated to heavy fighter duty and had to be escorted by Yak-3s. The Yak-9K saw only limited use due to the unreliability of the NS-45 and to airframe performance issues caused by the NS-45 and by the larger fuel tanks used on the Yak-9K; it also saw little use because of a reduced number of German bombers. ;Yak-9D A long-range version of the Yak-9 with fuel capacity increased from , giving a maximum range of . Its combat usefulness at full range was limited by a lack of radio navigation equipment, and a number of aircraft were used as short-range fighters with fuel carried only in inner wing tanks. The time to complete a circle was 19–20 seconds. The weight of fire was . ;Yak-9TD A Yak-9D with an NS-37 cannon and provision for 4 ×
FAB-50 bombs under the wings. ;Yak-9B A fighter-bomber version of the Yak-9D (factory designation
Yak-9L) with four vertical tube bomb bays (in a 2×2 arrangement) aft of the cockpit with capacity for up to 4 ×
FAB-100 bombs or 4
PTAB cassettes with 32 × bomblets each, although normally only of weapons were carried in the front bomb bays. The Yak-9B was put into limited production but did not prove successful enough to be put into wide-scale production. Difficulties in loading bombs, poor handling with a full bomb and fuel load and lack of bombsight or other aiming equipment limited its combat usefulness. ;Yak-9DD A Yak-9D or Yak-9T modified for longer range by a larger fuel capacity of which increased the maximum range to . Radio navigation equipment for night and poor weather flying was added. The Yak-9DD was used primarily to escort
Petlyakov Pe-2 and
Tupolev Tu-2 bombers although it proved less than ideal for this role due to an insufficient speed advantage over the bombers. In 1944, several Yak-9DD fighters were used to escort
B-17 Flying Fortress and
B-24 Liberator bombers attacking targets in
Romania using the
Ukraine-Romania-
Italy routes. ;Yak-9M A Yak-9D with the cockpit moved to the rear like the Yak-9T, as well as numerous fixes and improvements based on experience with previous versions. ;Yak-9M PVO A Yak-9M with slightly reduced fuel capacity, the
Klimov VK-105PF2 engine with , and radio and navigational equipment for night and adverse weather flying for
PVO Strany. ;Yak-9 MPVO A single-seat night fighter aircraft, equipped with a searchlight and an RPK-10 radio compass. ;Yak-9S A Yak-9M with a
Klimov VK-105PF engine, a new propeller, and armament consisting of 1 ×
Nudelman-Suranov NS-23 cannon with 60 rounds, and 2 ×
Berezin B-20 cannons with 120 rounds. It did not enter production due to its poor performance compared to the
Yak-3 and Yak-9U. ;Yak-9R A single-seat tactical reconnaissance aircraft. ;Yak-9P This aircraft was the last and the most advanced version of the Yak-9 fighter, which became the pinnacle of development among A. S. Yakovlev's piston-engined fighters. The Yak-9P (Product P) that appeared in 1946 was a modification of the Yak-9U fighter of composite construction. Unlike its predecessor, it had all-metal wings with elliptical tips. By this time, the manufacture of high-strength aluminum alloys was established in the Soviet Union, simplifying aircraft operation and increasing aircraft service life. ;Yak-9P (VK-107) A Yak-9U with an all-metal wing. "Yak-9P" in this case was a factory designation different from the Yak-9P with two ShVAKs described above. ;Yak-9PD A high-altitude interceptor (unrelated to the two other Yak-9P variants described above) with the
Klimov M-105PD engine, designed specifically to intercept
Luftwaffe Junkers Ju 86P high-altitude reconnaissance aircraft overflying
Moscow in 1942–1943. Poor performance due to the unreliable engine dramatically improved with adoption of the
Klimov M-106PV with
water injection, with the aircraft reaching during testing. The armament was reduced to the
ShVAK cannon only to save weight. ;Yak-9U (VK-105) A Yak-9T with the
Klimov VK-105PF2 engine and numerous aerodynamic and structural improvements introduced with the
Yak-3. The main visual difference from the Yak-9T was in the oil coolers in the wing roots, like on the Yak-3, and in that plywood covered the fuselage, instead of fabric. It differed visually from the Yak-3 only by the main landing gear covers. The armament increased to 1 ×
VYa cannon with 60 rounds and 2 × UBSs with 170 rounds each. The VYa cannon could be replaced by a ShVAK, B-20, or NS-37, the latter requiring removal of the starboard UBS machine gun. It did not enter production because the VYa was considered unsatisfactory and because the one cannon, one machine gun armament seen on previous models offered a significant increase in range. ;Yak-9U (VK-107) The definitive Yak-9 variant, the Yak-9U (VK-105) was equipped with the new
Klimov VK-107A engine, and with the ShVAK with 120 rounds replacing the VYa cannon. The weight of fire was . Early test flights in 1943 indicated that the only comparable Soviet fighter was the
Polikarpov I-185 prototype which was more difficult to fly and less agile due to higher weight. The prototype's top speed of at was second among production fighter aircraft in the world at the time only to the Mustang P-51B's achieved on military power. Early problems with overheating were fixed by enlarging the radiators and production aircraft had further improved aerodynamics. The time to complete a circle was 23 seconds. It was the best Soviet fighter at high altitude. ;Yak-9UV A two-seat trainer version of the Yak-9U (VK-107) with armament reduced to a single
Berezin B-20 cannon with 100 rounds. It did not enter production due to the introduction of jet aircraft. ;Yak-9UT A Yak-9U (VK-107) armed with 1 ×
Nudelman N-37 cannon with 30 rounds and 2 x
Berezin B-20 cannons with 120 rounds each, giving a total one-second burst mass of . Similarly to the Yak-9TK, it could be converted to replace the N-37 with a B-20, NS-23, or
N-45. Production aircraft carried the NS-23 instead of the N-37 cannon as the default armament. ;Yak-9-57 The Yak-9-57 was a one-off conversion of a Yak-9UT armed with a 57 mm cannon. The large caliber cannon did not protrude from the spinner cone like the Yak-9-37/45 models. ;Yak-9V A two-seat trainer version of Yak-9M and Yak-9T with the
Klimov VK-105PF2 engine and with armament reduced to 1 × ShVAK with 90 rounds. ;Modern replicas In the early 1990s, Yakovlev started limited production for the
warbird market of Yak-9 and
Yak-3 replica aircraft using original World War II equipment and
Allison V-1710 engines. These modern-built replicas using the Allison engines have counterclockwise-rotation props, unlike the originals, which strictly used clockwise-rotation Soviet V12 powerplants. ==Operators==