Background/Objectives: Aquatic exercise is attracting attention as a method of rehabilitation for children with cerebral palsy (CP). The purpose of this systematic review was to evaluate whether aquatic exercise for children with CP improves their walking ability and quality of life (QOL) and is enjoyable for them. Methods: A literature search was conducted on 2 August 2024 using three databases: PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials through Evidence-Based Medicine Reviews. Studies included in the review focused on aquatic exercise interventions for children with CP, with outcomes related to walking ability, QOL, or enjoyment. Studies that did not isolate the effects of aquatic exercise (except when combined with conventional interventions) were excluded. Two reviewers independently conducted screening and risk of bias assessments. Results: Seven studies involving 94 participants in total were included in the review. Three of these studies had a control group. All four studies reported improvements in walking ability, including walking endurance and efficiency. One of two studies showed improvement in health-related QOL (HRQOL) compared to the control group, whereas the other did not show significant differences between groups. All three studies that assessed enjoyment reported high levels of enjoyment of aquatic exercise. However, all studies were at risk of bias. Conclusions: The reviewed studies suggest that aquatic exercise for children with CP may be enjoyable and may improve walking ability. Further research is needed to accurately assess the effects of aquatic exercise and compare it to other interventions.