Some reviews suggest benefits of nonpharmacological interventions for informal caregivers of people with dementia and mild cognitive impairment. These benefits may transfer to the care-recipients (CRs) through increased caregiving capability, reduced burden and depression among caregivers, and decreased negative mood contagion. However, large-scale review on these effects on the CRs is lacking. We searched PsycINFO, CINAHL with Full Text, MEDLINE, and PubMed from inception to end of 2020 and found 142 articles that reported randomized controlled trials (RCTs) of caregiver interventions using CR outcomes. Interventions were found to reduce neuropsychiatric symptoms (NPS) in general and behavioral and mood disturbance specifically, enhance cognition and quality of life, and delay institutionalization and mortality, with care coordination/case management, educational intervention with psychotherapeutic components (psychoeducation-b), and direct training of the CR (with caregiver involvement) being the more potent interventions. The kinds of benefit depend on the types of intervention. NPS was reduced by psychoeducation-b, care coordination/case management, and CR training. Cognition and quality of life were enhanced by CR training and care coordination/case management, respectively. Institutionalization was delayed by multicomponent interventions and respite (based on one study). However, the effects were generally small to very small. Together with existing findings on caregiver outcomes, a tripartite scaffolding model of caregiver support is proposed. The model is composed of three components: (a) care coordination/case management (i.e., enhanced usual care), (b) psychoeducation-b, and (c) CR training. Future directions in terms of developing consensual guidelines, a registry of intervention manuals, and family-centered programs with flexibility in delivery are discussed.