Background: Overweight/obesity is an emerging health concern among African children. The aim of this study was to summarise available evidence from school-based interventions that focused on improving nutrition and physical activity knowledge, attitude, and behaviours, and weight status of children aged 6–15 years in the African context. Methods: Multiple databases were searched for studies evaluating school-based interventions of African origin that involved diet alone, physical activity alone, or multicomponent interventions, for at least 12 weeks in duration, reporting changes in either diet, physical activity, or body composition, and published between 1 January 2000 and 31 December 2018. No language restrictions were applied. Relevant data from eligible studies were extracted. Narrative synthesis was used to analyse and describe the data. Results: This systematic review included nine interventions comprising 10 studies. Studies were conducted among 9957 children and adolescents in two African countries, namely South Africa and Tunisia, and were generally of low methodological quality. The sample size at baseline ranged from 28 to 4003 participants. Two interventions reported enrolling children from both urban and rural areas. The majority of the study participants were elementary or primary school children and adolescents in grades 4 to 6. Participants were between the ages of 12.4 and 13.5 years. All but one intervention targeted children of both sexes. Four studies were described as randomised control trials, while five were pre- and post-test quasi-experiments. Except for one study that involved the community as a secondary setting, all were primarily school-based studies. The duration of the interventions ranged from four months to three years. The interventions focused largely on weight-related behaviours, while a few targeted weight status. The results of the effectiveness of these interventions were inconsistent: three of five studies that evaluated weight status (body mass index (BMI), BMI z-score, overweight/obesity prevalence), three of six studies that reported physical activity outcomes (number of sports activities, and physical activity duration ≥ 30 min for at least six days/week), and four of six reporting on nutrition-related outcomes (number meeting fruit and vegetable intake ≥ 5 times/day) found beneficial effects of the interventions. Conclusion: Given the dearth of studies and the inconsistent results, definite conclusions about the overall effectiveness and evidence could not be made. Nonetheless, this study has identified research gaps in the childhood obesity literature in Africa and strengthened the need for further studies, the findings of which would contribute valuable data and inform policy.