Negative cognitions and emotions about work during off-job time (e.g., worry about work tasks) can hinder the necessary recovery from work and lead to impaired occupational well-being. To better understand when this negative cognitive-affective involvement arises, we considered simultaneous and interactive effects of external and individual factors. Specifically, we investigated whether job demands (i.e., time pressure, cognitive demands, emotional demands) and maladaptive thinking patterns are independently and jointly related to negative cognitive-affective involvement and whether this is in turn associated with impaired occupational well-being (i.e., emotional exhaustion, cynicism). Using a diary study, we collected daily data from 109 employees twice a day over two working weeks (N = 667 day-level observations). Multilevel analyses showed that negative cognitive-affective involvement mediates the relationship between job demands (i.e., cognitive demands, emotional demands) and the two occupational well-being indicators. The relationship between cognitive and emotional demands, respectively, and negative cognitive-affective involvement is moderated by work-related maladaptive thinking patterns, with stronger relationships for employees reporting more frequent maladaptive thinking patterns. Moreover, work-related maladaptive thinking patterns moderate the indirect effects of job demands on occupational well-being via negative cognitive-affective involvement. Overall, we expanded the research on negative cognitive-affective involvement by providing a more comprehensive picture of its antecedents and outcomes. (PsycInfo Database Record (c) 2024 APA, all rights reserved).