The topic of an education-occupation mismatch of tertiary educated migrant workers in receiving countries is an important issue in contemporary research in international migration, especially in the context of growing international economic competition. In this article, we analyse the level of mismatch of tertiary educated migrant workers in the Czech labour market, with a particular focus on Ukrainian workers. Using a unique set of statistical data, several conclusions can be drawn from a longitudinal approach, as well as multiple regression analysis in order to identify possible determinants of the mismatch at a district level. First, the mismatch of tertiary educated migrants does exist and is growing over time. Second, it seems that the level of mismatch is higher in economically progressive districts with higher numbers of qualified domestic and foreign workers, which creates a higher level of competition in the labour market. As a result, a relatively higher share of tertiary educated migrant workers end up over-educated in professions they find in the secondary labour market in these districts. Using the example of Ukrainians, the progression of tertiary educated migrants into the Czech labour market over time faces rather limited vertical mobility, with a slight progression to more skilled occupations. This can be related to the complexity of factors from individual to institutional levels of analysis.