Changing family models have resulted in a large increase in the number of single-person households. This phenomenon has certain implications for society and the economy as single people often exhibit different behaviours, including their engagement in health-related physical activity, than those who are married and living with partners. However, the results of studies on determinants of physical activity in people of different marital status have been inconclusive. The aim of this study was to identify associations between physical activity and socioeconomic status in single and married urban adults. The study material consisted of 4,460 persons (1,828 single and 2,632 married and living with partners). A cross-sectional study was conducted in Wroclaw (Poland). A diagnostic survey-direct interview method was used. Two research tools were applied: the International Physical Activity Questionnaire Short Form (IPAQ-SF) and the Socioeconomic Status Questionnaire (S-ESQ). The level of respondents' physical activity was assessed following WHO recommendations. The descriptive statistics included the number and frequency of categories of dependent and independent variables as well as measures of association between them, i.e., crude and adjusted odds ratios. The odds ratio of meeting the WHO physical activity recommendations was almost 70% higher in single than in married respondents (OR = 1.67; CI [1.46-2.19]), and slightly more than 40% higher after adjusting for sex, age and education (aOR = 1.42; CI [1.21-1.67]). In both groups socioeconomic the respondents' status revealed a significant and slightly different association with their levels of physical activity. Occupational status and financial savings significantly affected the level of physical activity in single respondents, while net disposable income was a significant modifier of physical activity levels in respondents who were married or lived with their partners. Assessment of the levels and determinants of physical activity among people of different marital status should be continued and extended to other subpopulations. This will allow effective preventive and therapeutic measures to be taken for groups most at risk of hypokinesia. Programs aimed at improving physical activity accounting for the socioeconomic status and marital status of their beneficiaries are particularly important. © 2021 Puciato and Rozpara.