An ethno-confessional parallel society, a new actor in the European geopolitical space, is transforming the social and political fabric of Sweden. An institutionalised Muslim parallel society is emerging in vulnerable areas, such as marginalised immigrant districts of Swedish cities, through the efforts of Islamist political, social, and economic structures adhering to the religious and political doctrine of the Muslim Brotherhood. Committed to maintaining the Muslim identity, these organisations seek gradual Islamisation of the Swedish population through ideological influence on immigrants with a Muslim background. These efforts thwart cultural assimilation attempts and hinder the implementation of Swedish integration policy. The lack of research into the peaceful Islamisation of Swedish society and the related problems of Islamophobia, anti-Muslim racism, and radicalisation of Muslim youth lends urgency to investigating the influence of Islamist organisations on the Swedish Muslim immigrant community. This study analyses the literature, sources, and statistics on the essential aspects of Swedish Islamisation to provide a holistic picture of the formation of an ethnic-confessional parallel society in Sweden. The findings help evaluate the effectiveness of the national policy on confronting parallel societies, as well as of measures to promote democratic values as the foundation of a united Swedish society.