Factory workers make up a large proportion of China’s internal migrants and may be highly susceptible to job and adaptation stress, negative affective states, and Internet gaming disorder. This cross-sectional study investigated the relationships between job stress, psychological adaptation, negative affective states and IGD among 1,805 factory workers recruited by stratified multi-stage sampling between October and December 2019. Structural equation modeling was conducted to test the proposed mediation model. Among the participants, 67.3% were male and 71.7% were aged 35 years (...) old or below. The prevalence of probable depression, probable anxiety, and IGD was 39.3, 28.7, and 7.5%. Being male, younger age, and shorter duration of living in Shenzhen were associated with higher IGD scores. Job stress was significantly associated with IGD but not with negative affective states. Psychological adaptation was significantly associated with negative affective states. Negative affective states were positively associated with IGD. The indirect effect of psychological adaptation but not job stress on IGD through negative affective states was statistically significant. The observed psychological correlates and mechanisms are modifiable, and can inform the design of evidence-based prevention programs for depression, anxiety, and IGD in this population. (shrink)