Digitisation represents one of the key directions of adult education and training in the post-COVID-19 times, but direct empirical evidence of its scope among learners is rather scarce after 2021. Therefore, the general aim of this article is to investigate the current state of the use of online learning platforms and resources in adult education and training throughout Europe. For this purpose, we utilise data from a dedicated survey in the Czech Republic, Germany, Sweden, and the United Kingdom (n = 4,000) from 2022, which cover a wide range of digitalisation as measured by the Digital Economy and Society Index (DESI). Our findings are consistent with DESI in the overall levels of online learning across the four countries. Beyond this, we provide two main findings. First, the patterns of digitalisation are different in formal (FAE) and non-formal adult education (NFE). We identify two corresponding modes of platformization based on how and how much online learning platforms and resources are used. Second, factors of participation in online learning differ in some regards from factors of participation in AET in general. Therefore, online learning seems to constitute a new layer mediating participation in AET, possibly introducing new forms of inequalities.