Most research on self-determination theory applications in education focuses on competence and autonomy (Wigfield et al., 2019; Vallerand, 2000). After reviewing its mini theories and relevant recent research, this study argues that relatedness is central to motivation in higher education, as seen in a social context. Specifically, through relatedness, students are presented with alternatives to make choices. Such experience prescribes an internal perceived locus of causality, protects students from falling "prawn" to extrinsic motivation, and consequently improves intrinsic motivation (Deci & Ryan, 1985, p. 154). The hypothesized model is tested using PROCESS macro (Hayes, 2013) based on survey responses from 107 Chinese students regarding learning autonomy and intrinsic motivation, and the results show that relatedness has a complete mediation effect on the relationship between i) autonomy and motivation, ii) competence and motivation. In other words, relatedness complements why autonomy and competence lead to intrinsic motivation. Findings suggest new interpretations of best practices in higher education and open new directions for future research.