OBJECTIVE: This systematic review aimed to assess clinical outcomes of branched endovascular aortic repair (BEVAR) with inner branches (iBEVAR) and inner/outer branches (oBEVAR). DATA SOURCES: A systematic literature review was performed using the electronic bibliographic databases MEDLINE, Embase, Scopus, Web of Science, and the Cochrane Library up to May 2024. REVIEW METHODS: The review was designed and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Eligible studies reported death, technical failure, primary patency of target vessels (TVs), TV related complications, branch related re-interventions, and spinal cord ischaemia (SCI). Risk of bias was evaluated with the ROBINS-I tool. RESULTS: Twenty seven observational studies reporting a total of 1 780 patients treated with BEVAR and 6 633 TVs were included. A total of 386 patients (84.3%) were electively treated with iBEVAR while 72 (15.6%) were urgently treated vs. 845 (63.2%) and 491 (36.7%) with oBEVAR, respectively. The pooled estimate of 30 day mortality was 4.9% (95% confidence interval [CI] 2.9 - 8.2%) for iBEVAR and 7.6% (95% CI 4.9 - 11.7%) for oBEVAR. Overall mortality rates were 13.8% (95% CI 9.7 - 19.1%) for iBEVAR vs. 15.4% (95% CI 10.6 - 21.9%) for oBEVAR. The rate of SCI was 6.5% (95% CI 4.2 - 10.0%) in iBEVAR compared with 12.9% (95% CI 9.6 - 17.1%) in oBEVAR. Primary TV patency was similar between iBEVAR (97.3%, 95% CI 94.8 - 98.6%) and oBEVAR (97.6%, 95% CI 95.3 - 98.7%). Target vessel related complication rates were 2.9% (95% CI 2.0 - 4.1%) in iBEVAR vs. 3.9% (95% CI 2.7 - 5.6%) in oBEVAR. Technical failure rates were 4.1% (95% CI 2.4 - 6.9%) for iBEVAR vs. 5.7% (95% CI 3.5 - 9.1%) for oBEVAR. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) certainty was low or very low for all outcomes. CONCLUSION: Branched endovascular aortic aneurysm repair with inner and inner/outer branches has been used in elective and urgent cases, as well as across a variety of anatomies, with both designs demonstrating satisfactory clinical outcomes.