Pan-Finnicism (Finnish: panfennismi), also known as Pan-Fennicism or sometimes even referred to as Finno-Ugrism or even heimoaate (transl. "Kinship Ideology/Thought") is a pan-nationalist idea which advocates for the political or economic unification of the Finno-Ugric peoples. The idea is broad in its meaning and oftentimes it simply refers to the Finno-Ugric peoples, however on rare occasion it can be limited to only the Baltic Finnic peoples or to the Finnic peoples.

Pan-Finnicism was not an idea taken seriously until the formation of the Grand Duchy of Finland, and even with this sense of autonomy within the wider Russian Empire. Due to hundreds of years of Finland having been under Swedish Rule, a sense of Finnish identity was minor, even with the release of the Kalevala. Zacharias Topelius published an essay called “Den Finska Literaturen och dess Framtid" (transl. The Finnish Literature and Its Future) in 1844 where he states the following:

Two hundred years ago few would have believed that the Slavic tribe would attain the prominent (and constantly growing) position it enjoys nowadays in the history of culture. What if one day the Finnish tribe, which occupies a territory almost as vast, were to play a greater role on the world scene than one could expect nowadays? […] Today people speak of Pan-Slavism; one day they may talk of Pan-Fennicism, or Pan-Suomism. Within such a Pan-Finnic community, the Finnish nation should hold the leading position because of its cultural seniority […].

Within Pan-Fennicism, the idea that the Finns would hold superiority within such a union was not contested in Finland, as the idea that the Finns qualified as civilizers and awakeners within the Finno-Ugric community was not new, due to its aforementioned seniority. However, the Pan-Finnic Idea was often overlooked by the idea of Pan-Turanism, which was gaining ever more traction in the field of nationalist studies in academies in Finland. The field of studies on the Finno-Ugric peoples and their linguistic and cultural studies during these times often had a severe lack of Finnish scholars, due to a quite common consensus and hopes of many Finnish nationalists for the Finns and the Finno-Ugric peoples to not just be tribal people from nowhere, instead to showcase that the Finno-Ugric peoples and the larger Finno-Ugric family is a part of 'more respected cultures' and a civilizational affiliation. This led to Turanism becoming the mainstream in the Fennoman movement, and Arthur Castrén, who was a prominent fennomanist, believed that based on his research, the Finno-Ugric, Turkic, Mongolian and Tungusic languages were all of the same origins and family. He concluded that the Finns and their other ethnic relatives were from Central Asia, and were far from being a small, isolated people from the middle of nowhere:

I am determined to show the Finnish nation that we are not a solitary people from the bog, living in isolation from the world and from universal history, but are in fact related to at least one-sixth of mankind. Writing grammars is not my main goal, but without the grammars that goal cannot be attained.

August Ahlqvist, a close coworker of Castrén was of the opinion that the Finns were the perceived superior peoples within the Finno-Ugric family, due to the apparently more present fact of the Finns being more civilized than other Finno-Ugric peoples, however Ahlqvist's attitude had changed following research expeditions to the Volga, East Karelia and Siberia, he had become a suecophile, or at least an admirer of the Scandinavians for their bringing of Christianity and apparent civilization to the Finnish people. He changed his views to that of gratefulness towards the Swedes, and viewed the Finns as being privileged rather than explicitly superior. Ahlqvist's new opinions were proven controversial, and following a speech where he thanked the Swedes for saving the Finnish nation from the same fate as of that of the Finnic relative ethnic groups in Russia and said that the Finns owed a "debt of gratitude", this speech was antagonized much of the Fennoman millieu. Ahlqvist published the Suomen valta [fi] poem in 1860, in which Ahlqvist promoted the Greater Finland idea, advocating for the Finnish borders to expand, writing as follows; "Äänisjärvi, Pohjanlahti / Auranrantat, Vienansuu, / there is, Finnish, power / which is no one else's".

The developments of Pan-Finnicism were popular in Finland to an extent, however in other more literate regions such as Hungary, where ideas about being related to the ancient Scythians and other Turkic ideas about the Hungarian ethnic make-up were being formed due to their cultural isolation, the influence of the Turanian society and the perceived threat of Pan-Slavism which was promoted by the Russian Empire. Castrén says about the Hungarian reaction to Pan-Finnic ideas:

This is hardly surprising, for the idea of being related to the Lapps and the Samoyeds stirs us up, too. That same feeling—the commendable desire to have distinguished and splendid ancestors—has driven some of our scholars to seek our cradle in Greece or in the Holy Land. We must, however, give up all possible kinship with the Hellenes, with the ten tribes of Israel, with great and privileged nations in general, and console ourselves with the notion that “everyone is heir to his own deeds” and that real nobility has to be achieved with one's own skill. Whether the Finnish nation will manage to make itself a name in history is uncertain; what is certain is that the generations to come will judge us by our own achievements and not by those of our ancestors.