Biological invasions are one of the main problems of contemporary ecology. When considering invasive species a special attention should be paid to Asian weeds of Fallopia genus (knotweeds): Fallopia japonica, Fallopia sachalinensis, and their hybrid – Fallopia × bohemica, which is the most troublesome species among the Fallopia complex. The aim of this research was to determine distribution of three Fallopia taxa in urban environments using the example of the one of the largest Polish cities, Wrocław, and preferences of the examined species regarding their inhabiting different habitats in urban ecosystems. The presence of knotweeds was confirmed in over 23.0% of urban areas. The most commonly recorded species was Fallopia japonica, while Fallopia sachalinensis (a donor of pollen for female clones of Fallopia japonica) was rare. Despite this fact, their highly invasive hybrid occurs in approximately 6.8% of urban areas and accounts for 21.6% of the total number of all knotweed clones. It suggests that expansion of Fallopia × bohemica in the city advances, in most cases, in a vegetative way (as a result of rhizome regeneration).The highest number of knotweed sites was recorded in ruderal and greenfield sites, including, among others, illegal waste dumps, heaps, rubble, and debris fields. The investigation has shown that in urban conditions knotweeds are able to spread on soil with various pH ranges and nutrient content. Also, the higher content of heavy metals does not limit the expansion of Fallopia weeds – on the contrary, it can even enhance their competitiveness in relation to other plant species, which avoid toxic concentrations of heavy metals.