Macedonian nationalism (Macedonian: македонски национализам, pronounced [makɛdonski nat͡sionalizam]), sometimes referred to as Macedonianism, is a general grouping of nationalist ideas and concepts among ethnic Macedonians that were first formed in the second half of the 19th century among separatists seeking the autonomy of the region of Macedonia from the Ottoman Empire. The idea evolved during the early 20th century alongside the first expressions of ethnic nationalism among the Slavs of Macedonia. The separate Macedonian nation gained recognition during World War II when the Socialist Republic of Macedonia was created as part of Yugoslavia. Macedonian historiography has since established links between the ethnic Macedonians and various historical events and individual figures that occurred in and originated from Macedonia, which range from the Middle Ages up to the 20th century. Following the independence of the Republic of Macedonia in the late 20th century, the country's neighbours have disputed the existence of the Macedonian national identity, which is referred to in a derogatory way as Macedonism. Also, issue arose over what they consider an aggressive Macedonian nationalism, which holds more extreme beliefs such as an unbroken continuity between ancient Macedonians and modern ethnic Macedonians, also views connected to the irredentist concept of a United Macedonia, which involves large portions of Greece and Bulgaria, alongside smaller portions of Albania, Kosovo and Serbia.

During the first half of the second millennium, the concept of Macedonia on the Balkans was associated by the Byzantines with their Macedonian province, centered around Adrianople in modern-day Turkey. After the conquest of the Balkans by the Ottomans in the late 14th and early 15th century, the Greek name Macedonia disappeared as a geographical designation for several centuries. The background of the modern designation Macedonian can be found in the 19th century, as well as the myth of "ancient Macedonian descent" among the Orthodox Slavs in the area, adopted mainly due to Greek cultural inputs. However, Greek education was not the only engine for such ideas. During the early modern era, some Dalmatian pan-Slavic ideologists like Mavro Orbini believed the ancient Macedonians were Slavs. Under these influences in the 19th century some intellectuals in the region developed the idea on direct link between the local Slavs, the early Slavs and the ancient Balkan populations.

The local Slavs self-identified as "Bulgarian" on account of their language and socioeconomic status, thus the word Bulgarian had the connotation of poor, Slav-speaking peasant. Also, the local Slavs considered themselves as "Rum", i.e. members of the community of Orthodox Christians. This community was a source of identity for all the ethnic groups inside it and most people identified mostly with it.

At that time, the Orthodox Christian community began to degrade with the continuous identification of the religious creed with ethnic identity, while Bulgarian national activists started a debate on the establishment of their separate Orthodox church. Until the middle of the 19th century, the Greeks also called the Slavs in Macedonia "Bulgarians", and regarded them predominantly as Orthodox brethren, but the rise of Bulgarian nationalism changed the Greek position. As a result, massive Greek religious and school propaganda occurred, and a process of Hellenization was implemented among the Slavic-speaking population of the area. The very name Macedonia, revived during the early 19th century after the foundation of the modern Greek state, with its Western Europe-derived obsession with Ancient Greece, was applied to the local Slavs, which led to some "Macedonization" among Slavic-speaking population of the area. The idea was to stimulate the development of close ties between them and the Greeks, linking both sides to the ancient Macedonians, as a counteract against the growing Bulgarian cultural influence and Bulgarian Exarchate propaganda in the region. In 1845, for instance, the Alexander romance was published in Slavic Macedonian dialect typed with Greek letters. At the same time the Russian ethnographer Victor Grigorovich described a recent change in the title of the Greek Patriarchist bishop of Bitola: from Exarch of all Bulgaria to Exarch of all Macedonia. He also noted the unusual popularity of Alexander the Great and that it appeared to be something that was recently instilled on the local Slavs. However, Macedonian intellectuals, such as the Konstantin Miladinov, continued to call their land Western Bulgaria and worried that use of the new Macedonian name would imply identification with the Greek nation.

As a consequence, since the 1850s some Slavic intellectuals from the area adopted the designation Macedonian as a regional label, and it began to gain popularity. In the 1860s, according to Petko Slaveykov, some young intellectuals from Macedonia were claiming that they are not Bulgarians, but they are rather Macedonians, descendants of the Ancient Macedonians. Another basis on which they distinguished themselves from Bulgarians was that Macedonians were pure Slavs while the Bulgarians were Tatars and so on. Furthermore, they believed that the Bulgarian Exarchate is as oppressive as the Greek Patriarchate in terms of local ecclesiastic and scholarly matters. In a letter written to the Bulgarian Exarch in February 1874, Slaveykov reports that discontent with the current situation "has given birth among local patriots to the disastrous idea of working independently on the advancement of their own local dialect and what’s more, of their own, separate Macedonian church leadership." Per Slaveykov, the main task of his newspaper "Makedoniya" during 1870s, was to educate such misguided Grecomans there, who he called Macedonists.

According to Kuzman Shapkarev, as a result of Macedonists' activity, the Slavs in Macedonia had started to use the ancient designation Macedonians alongside the traditional one Bulgarians by the 1870s. However, Shapkarev notes that the name "Macedonians" had been "imposed on them by outsiders" (i.e., the Greeks), and that the Slavs in Macedonia were using the designation "Bulgarians" as peculiarly theirs, while referring to other Bulgarians as Shopi. Similarly, they referred to their own Macedono-Bulgarian dialect as Bulgarian ("bugarski") in opposition to the other Bulgarian dialects, which they called "shopski".

During the 1880s, after recommendation by Stojan Novaković, the Serbian government also began to support those ideas to counteract the Bulgarian influence in Macedonia, claiming the Macedonian Slavs were in fact pure Slavs (i.e. Serbian Macedonians), while the Bulgarians, unlike them, were partially a mixture of Slavs and Bulgars (i.e. Tatars). In accordance with Novaković's agenda this Serbian "Macedonism" was transformed in the 1890s, in a process of the gradual Serbianisation of the Macedonian Slavs.

By the end of the 19th century, according to Vasil Kanchov, the local Bulgarians called themselves Macedonians, and the surrounding nations called them Macedonians. In the early 20th century, Pavel Shatev witnessed this process of slow differentiation, describing people who insisted on their Bulgarian nationality, but felt themselves Macedonians above all. However a similar paradox was observed at the eve of the 20th century and afterwards, when many Bulgarians from non-Macedonian descent, involved in the Macedonian affairs, espoused Macedonian identity.