BACKGROUND: Dementia and mild cognitive impairment are significant contributors to disability and dependency in older adults. Current treatments for managing these conditions are limited. Exergaming, a novel technology-driven intervention combining physical exercise with cognitive tasks, is a potential therapeutic approach. OBJECTIVES: To assess the effects of exergaming interventions on physical and cognitive outcomes, and activities of daily living, in people with dementia and mild cognitive impairment. SEARCH METHODS: On 22 December 2023, we searched the Cochrane Dementia and Cognitive Improvement Group's register, MEDLINE (Ovid SP), Embase (Ovid SP), PsycINFO (Ovid SP), CINAHL (EBSCOhost), Web of Science Core Collection (Clarivate), LILACS (BIREME), ClinicalTrials.gov, and the WHO (World Health Organization) meta-register the International Clinical Trials Registry Portal. SELECTION CRITERIA: We included randomised controlled trials (RCTs) that recruited individuals diagnosed with dementia or mild cognitive impairment (MCI). Exergaming interventions involved participants being engaged in physical activity of at least moderate intensity, and used immersive and non-immersive virtual reality (VR) technology and real-time interaction. We planned to classify comparators as inactive control group (e.g. no treatment, waiting list), active control group (e.g. standard treatment, non-specific active control), or alternative treatment (e.g. physical activity, computerised cognitive training). Outcomes were to be measured using validated instruments. DATA COLLECTION AND ANALYSIS: Two review authors independently selected studies for inclusion, extracted data, assessed the risk of bias using the Cochrane risk of bias tool RoB 2, and assessed the certainty of the evidence using GRADE. We consulted a third author if required. Where possible, we pooled outcome data using a fixed-effect or random-effects model. We expressed treatment effects as standardised mean differences (SMDs) for continuous outcomes and as risk ratios (RRs) for dichotomous outcomes, along with 95% confidence intervals (CIs). When data could not be pooled, we presented a narrative synthesis. MAIN RESULTS: We included 11 studies published between 2014 and 2023. Six of these studies were pre-registered. Seven studies involved 308 participants with mild cognitive impairment, and five studies included 228 individuals with dementia. One of the studies presented data for both MCI and dementia separately. Most comparisons exhibited a high risk or some concerns of bias. We have only low or very low certainty about all the results presented below. Effects of exergaming interventions for people with dementia Compared to a control group Exergaming may improve global cognitive functioning at the end of treatment, but the evidence is very uncertain (SMD 1.47, 95% 1.04 to 1.90; 2 studies, 113 participants). The evidence is very uncertain about the effects of exergaming at the end of treatment on global physical functioning (SMD -0.20, 95% -0.57 to 0.17; 2 studies, 113 participants) or activities of daily living (ADL) (SMD -0.28, 95% -0.65 to 0.09; 2 studies, 113 participants). The evidence is very uncertain about adverse effects due to the small sample size and no events. Findings are based on two studies (113 participants), but data could not be pooled; both studies reported no adverse reactions linked to the intervention or control group. Compared to an alternative treatment group At the end of treatment, the evidence is very uncertain about the effects of exergaming on global physical functioning (SMD 0.14, 95% -0.30 to 0.58; 2 studies, 85 participants) or global cognitive functioning (SMD 0.11, 95% -0.33 to 0.55; 2 studies, 85 participants). For ADL, only one study was available (n = 67), which provided low-certainty evidence of little to no difference between exergaming and exercise. The evidence is very uncertain about adverse effects of exergaming compared with alternative treatment (RR 7.50, 95% CI 0.41 to 136.52; 2 studies, 2/85 participants). Effects of exergaming interventions for people with mild cognitive impairment (MCI) Compared to a control group Exergaming may improve global cognitive functioning at the end of treatment for people with MCI, but the evidence is very uncertain, (SMD 0.79, 95% 0.05 to 1.53; 2 studies, 34 participants). The evidence is very uncertain about the effects of exergaming at the end of treatment on global physical functioning (SMD 0.27, 95% -0.41 to 0.94; 2 studies, 34 participants) and ADL (SMD 0.51, 95% -0.01 to 1.03; 2 studies, 60 participants). The evidence is very uncertain about the effects of exergaming on adverse effects due to a small sample size and no events (0/14 participants). Findings are based on one study. Compared to an alternative treatment group The evidence is very uncertain about global physical functioning at the end of treatment. Only one study was included (n = 45). For global cognitive functioning, we included four studies (n = 235 participants), but due to considerable heterogeneity (I² = 96%), we could not pool results. The evidence is very uncertain about the effects of exergaming on global cognitive functioning. No study evaluated ADL outcomes. The evidence is very uncertain about adverse effects of exergaming due to the small sample size and no events (n = 123 participants). Findings are based on one study. AUTHORS' CONCLUSIONS: Overall, the evidence is very uncertain about the effects of exergaming on global physical and cognitive functioning, and ADL. There may be an improvement in global cognitive functioning at the end of treatment for both people with dementia and people with MCI, but the evidence is very uncertain. The potential benefit is observed only when exergaming is compared with a control intervention (e.g. usual care, listening to music, health education), and not when compared with an alternative treatment with a specific effect, such as physical activity (e.g. standing and sitting exercises or cycling). The evidence is very uncertain about the effects of exergaming on adverse effects. All sessions took place in a controlled and supervised environment. Therefore, we do not know if exergaming can be safely used in a home environment, unsupervised.