Lockdown measures during the COVID-19 pandemic have led to reductions in physical activity (PA) worldwide. Leading public health organizations have recommended the use of online exercise classes (OEC) to compensate the loss of regular exercise classes. As of now, no data are available on the uptake of OEC and on users’ attitudes. The aim of the current online survey was to assess the use of and attitudes towards OEC in Germany. Respondents indicated awareness and use of OEC, and levels of agreement with statements on OEC. Frequency of awareness and use of OEC according to PA status were calculated with contingency tables and the Χ2 test. Differences between users and non-users were tested with the Student’s t-test and the Mann–Whitney U test. Data on attitudes are presented as percentages, and Spearman correlations were calculated between attitudes and activity status, frequency of use, educational attainment, age and body mass index. A total of 979 datasets were analyzed. Of the respondents, 681 were aware of and 180, 118 and 84 used them <1 per week, 1–2 per week and ≥3 per week, respectively. Significantly more active respondents were aware of and used OEC compared to less active respondents. All in all, regular OEC use was quite limited. OEC was differentially attractive to people according to PA status, frequency of use, BMI and age. Tailoring OEC to current non-users and adding motivational support might enhance the regular use of OEC.