The COVID-19 pandemic accelerated digital technology adoption worldwide, yet limited evidence links post-pandemic multi-purpose online behavior with health outcomes and psychological well-being (PWB) in a single, integrated analysis. This study examines how digital device usage, breadth of online activity and self-reported Health Complaints relate to PWB across pre-COVID, during-COVID, and post-2023 periods. A cross-sectional survey of 622 respondents (collected in two pooled recruitment waves: Wave 1, \(n{=}323\); Wave 2, \(n{=}299\)) assessed device usage across three temporal periods, online purpose diversity, Health Complaints (12 indicators), and PWB (Ryff’s 18-item scale). Spearman correlations with permutation-based p-values and Benjamini–Hochberg FDR correction were used. Group comparisons employed permutation tests with Cohen’s d effect sizes and bootstrap 95% confidence intervals. K-means clustering (\(k{=}3\)) identified behavioral segments. PWB was negatively associated with Health Complaints count (\(\rho =-0.319\), \(p_{\text {FDR}}<0.05\)). Broader online purpose use correlated with more health effects (\(\rho =0.202\), \(p_{\text {FDR}}<0.05\)). High online-purpose users (top quartile) reported significantly more Health Complaints than low users (\(\Delta =+1.55\), \(d=0.54\), \(p_{\text {FDR}}<0.001\)). A partial Spearman correlation confirmed that this association persisted after controlling for total screen time (\(\rho _{\text {partial}}{=}0.154\), \(p_{\text {perm}}{<}0.001\), 95% CI [0.07, 0.23]), though the effect size was modest. Retrospective group-level estimates were higher for the during-COVID period than the pre-COVID baseline, with a lower estimate in Wave 2; these reflect between-wave, not within-person, comparisons. Three behavioral clusters emerged: low-usage/minimal-effects (\(n{=}142\)), high multi-device users (\(n{=}291\)), and higher health-effects/lower-PWB users (\(n{=}189\)). Among young, educated, urban adults, breadth of online activity was cross-sectionally associated with more self-reported adverse Health Complaints; both factors independently and collectively accounted for significant variance in PWB. These findings highlight the urgent need for digital wellness strategies that address activity diversity — not only total screen time — among young, educated, urban adults who represent the heaviest users of multi-purpose internet services in post-pandemic settings.
