Abstract This study uses job demands–resources and conservation of resources theories to propose that chronic levels of job burnout may aggravate the positive relationship of weekly job demands with week‐level burnout symptoms, dysfunctional coping, and self‐undermining. Specifically, we hypothesize that weekly job demands (workload and emotional demands) relate positively to maladaptive behaviors through weekly burnout symptoms, particularly when chronic burnout is higher (vs. lower). We collected data among 84 employees from various occupational sectors, who first filled out a general survey, and then completed weekly diary surveys every Friday, for five consecutive weeks (total n = 415 occasions). Results of multilevel analyses generally supported the hypotheses. Weekly job demands were positively related to weekly burnout and self‐undermining only when employees scored higher on chronic burnout. Moreover, as predicted, the results showed that job demands were most strongly related to dysfunctional coping and self‐undermining through weekly burnout symptoms for individuals higher (vs. lower) in chronic burnout. These findings highlight the interplay between weekly job demands and chronic burnout in the process of resource loss.