Gamification has become an increasingly popular approach in language education, particularly in vocabulary acquisition. Rooted in Self-Determination Theory (SDT), which emphasizes the psychological needs of autonomy, competence, and relatedness, gamified learning environments have enhanced motivation and engagement. This paper explores how SDT principles contribute to the effectiveness of gamified vocabulary learning, drawing on examples from language learning apps and classroom-based activities. By allowing learners to exercise choice, experience progress through feedback and rewards, and engage in social learning, gamification fosters intrinsic motivation and long-term retention. However, challenges such as over-reliance on extrinsic rewards and individual differences in gamification preferences highlight the need for balanced and adaptable learning designs. The study concludes by emphasizing the importance of meaningful game elements that align with SDT principles to ensure sustained engagement and effective vocabulary acquisition.