The Royal Yugoslav Air Force (Serbo-Croatian Latin: Jugoslovensko kraljevsko ratno vazduhoplovstvo, JKRV; Serbo-Croatian Cyrillic: Југословенско краљевско ратно ваздухопловство, ЈКРВ; (Slovene: Jugoslovansko kraljevo vojno letalstvo, JKVL); lit. "Yugoslav royal war aviation"), was the aerial warfare service component of the Royal Yugoslav Army (itself the land warfare branch of the Kingdom of Yugoslavia). It was formed in 1918 and existed until 1941 and the Invasion of Yugoslavia during World War II.

Some 18 aircraft and several hundred aircrew escaped the Axis invasion of April 1941 to the Allied base in Egypt, eventually flying with the Royal Air Force in Northern Africa initially and then with the Balkan Air Force in Italy and Yugoslavia, with some even going on to join the Soviet Air Force, returning to Yugoslavia in 1944.

Germany distributed captured Royal Yugoslav Air Force aircraft and spare parts to Romania, Bulgaria, Finland and the newly created Independent State of Croatia.

The Royal Yugoslav Air Force developed out of the Serbian Aviation Command, which had been created on 24 December 1912, and had been active during the Balkan Wars of 1912–1913. During World War I, the small Serbian Aviation Command had initially operated in support of the Royal Serbian Army and its defence of the country against concerted attacks by Austria-Hungary. After initial Serbian successes, in 1915 the Central Powers forced the Serbian Army to withdraw to Albania where the surviving elements of the army were evacuated. Serbian aviators were absorbed into French squadrons to support the French-led Allied force that pushed north from Salonika, and towards the end of the war, separate Serbian squadrons were again raised. After the end of World War I, in 1919 the South Slav peoples determined to form a new country, the Kingdom of Serbs, Croats and Slovenes, and the existing Serbian air corps became the basis for the military air service of the new state. The chief of the fledgling air force was the former head of the Austro-Hungarian Imperial and Royal Aviation Troops, Emil Uzelac.

Lack of funds meant that little could be done to improve military aviation in the first years of the new state, although in 1922, Uzelac went on a European tour to study military aviation in foreign armies. Efforts were also made to develop a civil aviation sector with a view to forming a reserve pool of pilots and mechanics. The following year, Uzelac retired, and the British military attaché noted that there were several former Russian Empire aviators serving in the air force, two of whom attempted to defect to the Soviet Union with an aircraft during that year. In 1924, the first Yugoslav-built aircraft was produced at the Ikarus plant in Novi Sad, albeit with a foreign-made engine. The next year, 150 Breguet 19 biplane light bomber and reconnaissance aircraft were purchased on credit from the French government, signalling the first significant expansion of the air force. The new aircraft were assembled at Novi Sad, then distributed to the other military aerodromes at Sarajevo, Mostar, Zagreb and Skopje. The Ikarus plant was producing training aircraft and seaplanes using Austrian engines captured at the end of World War I, and imported steel tubing and wire stays. In 1926, the aerodrome at Zemun was developed in order to provide a military airfield near the capital, Belgrade, and a military air race was held for the first time, with a gold cup presented by King Alexander.

By 1927, the air force had acquired Potez 25 biplanes and Dewoitine single-seater fighter aircraft, as well as some Hansa-Brandenburg and Hanriot training aircraft. The following year, a government aircraft factory at Kraljevo was completed, and a privately owned factory near Belgrade went into production, building French aircraft engines under licence. By the same year, the air force had also acquired Fizir F1V reconnaissance aircraft. In 1929, the British military attaché reported that the air force was making slow but steady improvements, but observed that the airfield at Novi Sad was the only one capable of supporting night flying. Chief among the deficiencies of the air arm were the lack of advanced repair and maintenance facilities at the various regional airfields such as those at Zagreb or Sarajevo. It was concluded that this meant the Yugoslav air force would be unable to keep aircraft in the air for any period of conflict beyond a few weeks. The factory at Kraljevo was apparently capable of producing around 50 licence-built Breguet 19 aircraft per year.

In 1930, workshops were completed at the airfields at Zagreb and Mostar, allowing for repairs and modifications to be carried out without transferring aircraft to the main factories and workshops closer to the capital. In May of that year, the first aircraft of entirely Yugoslav manufacture was completed at Kraljevo, and it was estimated that factory was capable of producing 100 Breguet 19 aircraft per year. At this time, the factory had a French workforce and was under French management, but the contract was due to expire in 1932, after which the Yugoslav government would be at liberty to produce whichever aircraft it could obtain licences to build. The privately owned Ikarus plant at Zemun continued to produce seaplanes of its own design as well as Potez 25 aircraft under licence. The strength of the air force was estimated at 26 squadrons of about twelve aircraft each, indicating a total of approximately 312 aircraft, although there were almost no reserve aircraft.

During 1931, no additional squadrons were raised, but a reserve of aircraft was built up, so that around 200 machines were stored at the various regional airfields. The British military attache assessed that the standard of pilot training remained deficient, with a significant number of aircraft being put out of action each year due to accidents. During the same year, the air force obtained three Hawker Fury aircraft for evaluation, two fitted with Rolls-Royce engines, and one with a Hispano-Suiza engine. This was viewed with alarm by the French, who had thus far had a strong influence over Yugoslav aviation procurement.