Background: The rapid expansion of online sports betting has raised concerns about its potential impact on individual health and public health. To further develop etiological models for gambling disorder (GD) in sports betting, it is essential to unravel the underlying causal processes. Recent studies have identified risky online gambling behavior as an early indicator of GD. This study focuses on impulsivity as a well-documented risk factor for GD and investigates whether increased impulsivity leads to risky online gambling behavior, which subsequently contributes to GD. Method: We recruited a final sample of n = 427 regular sports bettors from the online gambling provider Tipico. Impulsivity, risky gambling behavior, and GD symptoms were assessed three times at three-month intervals using a longitudinal cross-lagged panel design. Impulsivity and GD were assessed using a combination of online experimental tasks and questionnaires. Tipico provided player tracking data for all participants as a measure of risky gambling behavior. We used random intercept cross‐lagged panel models to test our hypotheses. Results: We found partial support for the role of impulsivity in the development of GD. Specific impulsivity facets, such as impulsive choice and certain impulsive personality traits, were associated with subsequent GD symptoms. However, there was no evidence that impulsivity directly predict risky betting behavior, nor did risky betting mediate the relationship between impulsivity and GD severity. Conclusions: These results emphasize the complexity of pathways toGD in online sports betting. While impulsivity contributes to GD, its effects appear not to operate via risky betting behavior. Future work should explore multifactorial models that incorporate emotional, cognitive, and environmental mediators to better understand the emergence of GD in online contexts.