In the middle of the 19th century the Bulgarian community began to take on an important position in the economic life of Istanbul. The Bulgarian community increased in number through the engagement of more and more Bulgarians as merchants, shopkeepers and textile workers, and the Bulgarians in Istanbul became the protagonists of the Bulgarian Church Movement. In 1870 Sultan Abdulaziz issued the establishment of the Bulgarian Exarchate and the Bulgarians became a new Orthodox millet. They established their millet organizations and institutions and started to be registered as a separate group in the official Ottoman population registers. Although there are a few studies about the population structure and economic activities of this community, the Ottoman archival sources have not yet been utilized properly. This study aims to present the population structure, the settlement areas, as well as the professions and cultural organizations of the Bulgarian community in Istanbul at the beginning of the 20th century by utilizing Ottoman population registers and other archival documents. In this way, the estimated figures and information about Bulgarians in Istanbul taken from memoirs, will be corrected with more precise figures taken from archival registers and consequently a more realistic picture will be given. Moreover, the paper also tries to evaluate the general role of the Bulgarian community in the social and economic life of the capital of the Empire.