Background: Low in-hospital mobility is widely acknowledged as a major risk factor in acquiring hospital-associated disabilities. Various predictors of in-hospital low mobility have been suggested, among them older age, disabling admission diagnosis, poor cognitive and physical functioning, and pre-hospitalization mobility. However, the universalism of the phenomena is not well studied, as similar risk factors to low in-hospital mobility have not been tested. Methods: The study was a secondary analysis of data on in-hospital mobility that investigated the relationship between in-hospital mobility and a set of similar risk factors in independently mobile prior to hospitalization older adults, hospitalized in acute care settings in Israel (N = 206) and Denmark (N = 113). In Israel, mobility was measured via ActiGraph GT9X and in Denmark by ActivPal3 for up to seven hospital days. Results: Parallel multivariate analyses revealed that a higher level of community mobility prior to hospitalization and higher mobility ability status on admission were common predictors of a higher number of in-hospital steps, whereas the longer length of hospital stay was significantly correlated with a lower number of steps in both samples. The risk of malnutrition on admission was associated with a lower number of steps, but only in the Israeli sample. Conclusions: Despite different assessment methods, older adults’ low in-hospital mobility has similar risk factors in Israel and Denmark. Pre-hospitalization and admission mobility ability are robust and constant risk factors across the two studies. This information can encourage the development of both international standard risk evaluations and tailored country-based approaches.