The striatum orchestrates the timing and vigor of movement through its direct and indirect pathways. The indirect pathway has been viewed as primarily suppressing motor output traditionally. However, recent studies indicate that dopamine D2 receptor-expressing medium spiny neurons (D2-MSNs) within the indirect pathway can either facilitate or inhibit behavior depending on context, thus exerting bidirectional control over movement. Accordingly, this review first synthesizes evidence on the diverse regulatory functions of D2-MSNs across multiple domains of motor control, including movement initiation, speed regulation, habit formation, and avoidance. It then examines the mechanisms by which D2-MSNs regulate movement at three levels: the characteristic patterns of receptor distribution on these neurons, their interactions with other striatal interneuron populations, and the organization of downstream neural circuits. Finally, the significance of D2-MSNs in various movement disorders is considered, in order to refine understanding of their role within basal ganglia models of motor control and to inform more precise therapeutic strategies for movement disorder-related conditions.