The purpose of this article is to determine the level of millennials’ openness to innovative services offered by FinTech in Poland against the background of financial behaviours displayed in this area by the millennials in the USA. During the analysis of the level of openness to FinTech services of the examined generation, the value of FinTech adoption index for the millennials was determined and the authors developed five-step scales of openness in terms of FinTech service type (objective approach) and the number of FinTech entities (subjective approach). The authors formulated the following research hypothesis: the degree of the millennials’ openness to innovative services offered by FinTech in Poland does not differ significantly from the financial behaviours displayed in this area by the millennials in USA. In order to verify the hypothesis, we used the methods of scientific description, review and critical analysis of analytical reports on the FinTech phenomenon, statistical methods and the CAWI method. The necessary empirical data of qualitative and quantitative nature were collected through a survey conducted on a representative sample of 1236 Polish millennials in December 2019. The study results have demonstrated that both in the USA and in Poland, a high level of openness of the millennial generation to FinTech services is observed. FinTech Adoption Index for US millennials was 59% in 2017, while the value of this ratio in Poland in 2019 was around 75%. The analysis of financial behaviours of the examined generation proves that in Poland, just like in the USA, payment services were the most popular.