The concept of crowdsourcing, categorized into internal and external crowdsourcing, emerged relatively recently. Internal crowdsourcing gained increasing popularity in Chinese organizations. Based on the self-determination theory (SDT), this study advances the theoretical understanding of the effects of employee motivation antecedents (the three basic psychological needs: autonomy, competence, and relatedness) on participation effort in internal crowdsourcing activities. Through an online survey, 435 employees in information technology organizations in southern China completed the questionnaires which used for statistical analysis and hypotheses testing. It was found that the three basic psychological needs significantly positively impacted employees’ intrinsic motivation, with autonomy having the most significant effect. Furthermore, only the needs for autonomy and competence were significantly positively associated with extrinsic motivation. A positive relation was observed between intrinsic motivation and employee participation effort in internal crowdsourcing. Although no direct relationship was revealed between extrinsic motivation and employee participation effort, an indirect effect of extrinsic motivation on employee participation via intrinsic motivation was observed, which aligned with one of the main concepts of SDT, the internalization process of extrinsic to intrinsic motivation. Accordingly, the SDT model is applicable to information technology organizations in China based on the findings of this study.