The current systematic review was performed to assess the functional outcomes of implant-prosthetic treatment on patients who have had surgical resection of oral cavity tumors. The assessment of function, satisfaction, or quality of life (QoL) were the major outcomes that evaluated preoperative and/or before and after implant-prosthetic treatment. Only eight published studies fulfilled the inclusion criteria. Three publications evaluated chewing ability, masticatory performance, and neuromuscular function, and the other five publications used questionnaire as a method of assessment. These publications mainly reported on implant-prosthetic treatment in mandibulectomy patients. It was found that implant-retained prosthesis had a beneficial effect on masticatory performance and masseter muscle activity on the defect side, but not on the non-defect side. Swallowing threshold performance and jaw movement parameters showed no significant differences between non-implant-retained prosthesis and implant-retained prosthesis. Significant improvement in prosthesis and patients' satisfaction with implant-retained prosthesis compared to non-implant-retained prosthesis was observed. However, general improvement in patients' QoL was not observed after implant-prosthetic treatment. Patients with intraoral resection might benefit from implant-retained prosthesis with regard to masticatory function and satisfaction. However, future clinical trials with an adequate sample size are needed to identify the group of patients who are likely to benefit from the implant-prosthetic treatment modality.