Almásy continued to support King Karl of Austria during the interwar period. On two occasions, he drove Karl to Budapest, Hungary, when he tried to get his throne back. It may be that the King bestowed him unofficially with the title of count that Almásy only used outside of Hungary.
After 1921, Almásy worked as a representative of the Austrian car firm Steyr Automobile in Szombathely, Hungary, and won many car races in the Steyr colors. He also organized hunting trips in the Kingdom of Egypt for visiting Europeans.
In 1926, during his drive from Egypt to the Sudan along the Nile, Almásy developed an interest in the area and later returned there to drive and hunt. He also demonstrated Steyr vehicles in desert conditions in 1929 with two Steyr lorries and led his first expedition to the desert.
In 1932, Almásy left to find the legendary Zerzura, "The Oasis of the Birds," with three Britons, Sir Robert Clayton, Commander Penderel, and Patrick Clayton. They were all sponsored by Prince Kemal el Din. The expedition used both cars and an aeroplane. They discovered prehistoric rock art sites, including the Cave of Swimmers in Uweinat and Gilf Kebir. In 1933, Almásy claimed that he found the third valley of Zerzura in Wadi Talh.
Almásy had succeeded in turning from an autodidact into a serious explorer. He was given the nickname Abu Ramla ("Father of the Sands") by his Bedouin friends. However, by the mid-1930s, the time for research and adventure was drawing to a close.
In 1932, Almásy's former sponsor Clayton died — not from a crash-landing as described in "The English Patient" — but of an infection from a desert fly contracted in the Gilf Kebir region. However, Clayton's wife did die one year later (1933) in a mysterious plane crash.
Almásy recorded some of his adventures in the book Az ismeretlen Szahara (The Unknown Sahara), first published in 1934 in Budapest. The German edition, under the title Unbekannte Sahara. Mit Flugzeug und Auto in der Libyschen Wüste (The Unknown Sahara. By Aeroplane and Car in the Libyan Desert), was published five years later (1939) by Brockhaus in Leipzig. It contains accounts of his most sensational discoveries like the one of the Jebel Uweinat (the highest mountain of the Eastern Sahara desert), of the rock paintings in the Gilf Kebir and of the lost oasis of Zerzura.
Almásy's role in relation to the Gilf Kebir was not that of a discoverer. The Bedouins already knew it was there, but tended to avoid the caves except when searching for stray livestock, attributing the cave paintings inside to djinn or unpredictable spirits. Egyptian Prince Kemal ed Din wrote an article about Gilf Kebir for National Geographic in 1921. What Almásy did was to map and enter each cave and draw the paintings inside.
In 1935, Almásy may have provided Italian Marshal Italo Balbo with intelligence concerning the feasibility of advancing into Egypt and the Sudan from Italian North Africa (Africa Settentrionale Italiana, or ASI). This was during the Abyssinia Crisis and Balbo was the Governor-General of ASI.
The German military intelligence service (Abwehr) recruited Almásy in Budapest. As a Hungarian reserve officer, he was assigned to the German Air Force (Luftwaffe) as a Captain (Hauptmann) and assigned to the Afrika Korps. In 1941 and 1942, he worked with the German troops of Erwin Rommel using his desert experience and led military missions. During "Operation Salaam," Almásy infiltrated two German spies through enemy lines in a manner similar to the Allied Long Range Desert Group. "Operation Salaam" was not a covert operation. Almásy and his team wore German uniforms. They also used American cars and a truck with German crosses surreptitiously incorporated as part of the vehicles camouflage pattern. Almásy delivered the German (Abwehr) agents Hans Eppler and Peter Stanstede to Cairo in the same way. Rommel subsequently promoted Almásy to major.
As late as 1944, Almásy was involved with "Operation Dora." This was a Greece-based operation to set up a base at an abandoned Italian airstrip in the Libyan Desert. The base would be used to locate German agents into North Africa to set up listening posts. Even this late in the war, the operation almost succeeded.
The details of Almásy's role in World War II are likely to remain unclear. For delivering spies, he received the Iron Cross (Eisernes Kreuz) from Rommel. He was, however, never a spy nor a Nazi. He was a Conservative Hungarian Royalist whose loyalty was to Hungary.
After the end of the North African Campaign, Almásy relocated to Turkey where he became involved in a plan to cause an Egyptian revolt which never materialized. He then returned to Budapest where with his contacts from the Roman Catholic Church he helped save the lives of several Jewish families at a time when Jews were being sent to concentration camps.