This data set includes replication data for the article Problematic Internet Use Predicts Lesser Satisfaction with Life, but Psychological Distress Acts as a Mediator published in the journal Cyberpsychology, Behavior, and Social Networking, 28(9), 616-622 (September 10th, 2025). Participants of the present study were N = 7,536 adults from six European countries: the UK (n = 1,204); Switzerland (n = 1,227; French-speaking); Spain (n = 1,212); Poland (n = 1,456); Czech Republic (n = 1,212); and Germany (n = 1,225). Participants completed questionnaires including scales for the following variables via online panels. The overall mean age was 45.73 years old (standard deviation [SD] = 15.69); 48.7% identified as men (n = 3,669), and 50.8% as women (n = 3,827); 0.3% identified as nonbinary, transgender, or other (n = 24), and 0.2% preferred not to say (n = 16). Variables are as follows. Country (1 = United Kingdom; 2 = Switzerland (francophone); 3 = Spain; 4 = Poland; 5 = Czechia; 6 = Germany). Gender (1 = Male; 2 = Female; 3 = Any other gender identity; 4 = Other (please describe); 5 = Prefer not to say). Age = Age in years. Satisfaction with life scale items SWL01 through SWL05 with responses coded: 1 = Strongly disagree; 2 = Disagree; 3 = Slightly disagree; 4 = Neither agree nor disagree; 5 = Slightly agree; 6 = Agree; 7 = Strongly agree. Depression, anxiety, and stress scale items DAS01 through DAS21 with responses coded: 0 = Did not apply to me at all; 1 = Applied to me to some degree, or some of the time; 2 = Applied to me to a considerable degree or a good part of time; 3 = Applied to me very much or most of the time. Problematic internet use scale items PIU01 through PIU09 with responses coded: 1 = Never; 2 = Rarely; 3 = Sometimes; 4 = Often; 5 = Always/almost always.