Background and Objectives: Children with Developmental Coordination Disorder (DCD) show substantial motor and balance difficulties that affect daily activities. Although action observation (AO) and motor imagery (MI) are effective in other neurological conditions, their impact in DCD remains underinvestigated. This review explores the preliminary evidence of AO- and MI-based interventions for improving motor and functional outcomes in children with DCD. Methods: A systematic search of PubMed, Scopus, and Web of Science identified randomized controlled trials and controlled trials published in the last 15 years evaluating AO and MI interventions in children with DCD. Two independent reviewers conducted the screening of the studies, data extraction, and the risk-of-bias assessment using RoB2 and ROBINS-I. The review followed PRISMA reporting guidelines and was pre-registered on the PROSPERO database (CRD420251084196). Results: Of 320 records initially identified, seven studies, involving 199 children with DCD (aged 5–12 years), were included. Interventions varied from single-session to multi-session protocols (1–16 sessions) and included AO, MI, or a combination of both (AO + MI), with heterogeneous control conditions. Within these studies, the outcomes were primarily assessed using standardized motor coordination measures (MABC/MABC-2, DCDQ), planning tasks, and performance-based activities of daily living (ADLs) measures. Improvements were reported in motor imagery tasks, planning, and functional task performance. However, RCTs and CTs were identified to have a moderate and high risk of bias, respectively. Conclusions: The present review suggests that AO and MI, either alone or in combination, may enhance motor planning, coordination, and daily functional skills in children with DCD, supporting internal motor representations and predictive motor control, reflecting functional gain in motor skills and ADL performance. Interestingly, these mental training approaches can be applied in clinical and everyday settings and are suitable for supporting these processes, with VR-based combinations representing a promising, but exploratory, approach. Although critical heterogeneity and a moderate risk of bias remain, the findings need to be interpreted with caution and require further investigation.