Introduction: Individuals suffering from overweight or obesity frequently experience weight-based stigmatization. The widespread belief that weight is a matter of personal will and self-control results in various weight-based stereotypes (e.g., laziness, lack of self-discipline, or neglect). Objective: Based on the modified version of the Weight Bias Internalization Scale (WBIS-M), a short form for the economic assessment of weight bias internalization in the general population was compiled and validated. Methods: A three-item short form (WBIS-3) was derived based on data from a representative sample of the German population (n = 1,092). This new short form was validated in a second representative population sample (n = 2,513). Item characteristics and internal consistency were obtained. Measurement invariance was tested. Construct validity was established via the correlation with theoretically related constructs (depression, anxiety, eating behavior, discrimination, weight status). To establish scale validity, all analyses were performed for the whole sample as well as for the subsample of individuals with overweight. Age- and gender-specific population norms were provided. Results: The WBIS-3 exhibited excellent psychometric properties. Internal consistency was α = 0.92. Strong measurement invariance was confirmed regarding age, gender, discrimination, and weight status in both the whole sample as well as the overweight subsample. Conclusions: The WBIS-3 constitutes a valid and economical tool for the assessment of weight bias internalization in epidemiological contexts. Measurement invariance allows for an unbiased comparison of means, correlation coefficients, and path coefficients within structural equation modeling across groups.