BACKGROUND: Managing medial compartment knee osteoarthritis (OA) with anterior cruciate ligament (ACL) deficiency, particularly in younger, active patients, remains challenging. Medial unicompartmental knee arthroplasty (UKA) combined with ACL reconstruction (ACLR) (UKACL) has gained interest, yet outcomes remain incompletely defined. This systematic review aims to evaluate the clinical effectiveness, implant survivorship, complications, and patient-reported outcomes after combined UKA and ACLR in end-stage medial OA with ACL deficiency. METHODS: We systematically searched PubMed, Embase, Scopus, and Web of Science. Studies reporting outcomes of UKA performed with ACLR were included; case reports, technical notes, and biomechanical studies were excluded. Risk of bias was assessed with ROBINS-I V2. We extracted clinical outcomes, implant survival, complications, radiographic findings, and validated functional scores. RESULTS: Fourteen studies comprising 353 patients met the inclusion criteria. Reported survivorship consistently exceeded 90% at 10 years. Ten revisions were reported, most commonly for lateral OA progression. Overall complication rate was 9.06% with no difference between mobile-bearing and fixed-bearing designs. Mobile-bearing implants had a slightly higher bearing dislocation risk, whereas fixed-bearing designs showed marginally higher polyethylene wear. Functional outcomes improved across studies. CONCLUSION: Combined UKA and ACLR appears effective for younger, active patients with isolated medial OA and ACL deficiency, yielding high survivorship and consistent functional gains. Given heterogeneity among studies, high-quality, long-term randomized trials are needed to refine patient and implant selection. LEVEL OF EVIDENCE: Level IV, systematic review of nonrandomized studies. See Instructions for Authors for a complete description of levels of evidence.