Objectives: This study investigated the differential impact of work arrangements (on-site, hybrid, remote) on employee well-being. It tested a model where work mode predicts basic psychological needs (Hypothesis [H] 1), these needs predict work satisfaction (H2), and core self-evaluations (CSE) predict needs fulfilment (H4), ultimately examining the mediating role of needs in the work mode and CSE-satisfaction relationships (H3 and H5). Material and Methods: A cross-sectional online survey was conducted among 612 working adults from southern Poland, recruited from various companies in November 2023 – March 2024. Measurements included Core Self-Evaluation Scale (ω = 0.846), Basic Psychological Needs Satisfaction and Frustration Scale (ω = 0.764–0.894), and 4-item work satisfaction subscale from the Copenhagen Psychosocial Questionnaire (COPSOQ-II) (ω = 0.866). Statistical analyses employed robust ANOVA, hierarchical regression with bootstrapped confidence intervals, and bias-corrected bootstrapped mediation analyses. Results: Work mode predicted basic psychological need for autonomy (F = 6.55, p = 0.006), competence (F = 10.23, p < 0.001), and work satisfaction (F = 16.80, p < 0.001), with on-site workers reporting the lowest levels of needs fulfilment and work satisfaction (H1a). Need for relatedness did not differ by work mode (H1b not supported). Autonomy (β = 0.31, p < 0.001) and competence (β = 0.28, p < 0.001), but not relatedness, were significant predictors of work satisfaction (H2 partially supported). Core self-evaluations was a significant predictor of all needs (H4 supported). Only autonomy satisfaction significantly mediated the relationship between work mode and work satisfaction (H3 partially supported) and similarly CSE and work satisfaction (H5 partially supported). Conclusions: Core self-evaluations are a universal predictor of work satisfaction regardless of work arrangement. However, the mediating role of autonomy does not work in the online context. Study limitations include a non-random, cross-sectional study sample and geographic specificity to southern Poland. Int J Occup Med Environ Health. 2026;39(2)