BACKGROUND: Evidence is lacking to inform how micronutrient deficiencies should be prevented and treated before metabolic-bariatric surgery to optimize patient outcomes. OBJECTIVE: This systematic review aimed to examine the effect of preoperative repletion strategies for micronutrient deficiencies on micronutrient biochemistry, quality of life, and complication rates among candidates for metabolic and bariatric surgery compared with usual care, alternate strategies, or no treatment. METHODS: PubMed, Embase, CINAHL, and CENTRAL was searched in April 2024. A grey literature search was updated in April 2024 via Google search. Eligible observational and interventional studies were those that provided micronutrient repletion before the surgery and measured micronutrient status pre- and/or postsurgery. Studies with participants who were pregnant, lactating, or elected jejunocolic bypass, jejunoileal bypass, vertical banded gastroplasty, and biliopancreatic diversion were excluded. Risk of bias was assessed using the Academy of Nutrition and Dietetics Quality Criteria Checklist. Findings were narratively synthesized and the Grading of Recommendation, Assessment, Development and Evaluations was adopted when applicable. Twenty studies (n = 27 groups) were included (n = 15 observational; n = 5 interventional). RESULTS: Strategies targeted vitamins A, D, E, B6, B12, C, thiamin, folate, calcium, iron, selenium, and zinc, including chronic dosing of oral supplements and multivitamins (n = 21), megadoses of oral supplements (n = 1), intramuscular injection (n = 1), intravenous infusion (n = 1), and a mix of injection and oral supplements (n = 3). Preoperative repletion strategies varied in efficacy. Chronic dosing of oral supplements increased vitamin D levels (n = 4 interventional studies; Grading of Recommendation, Assessment, Development and Evaluations rating: moderate). Multivitamins did not improve vitamin B12 status but improved status of vitamin B6, vitamin C, and folate. Iron infusion (n = 1) increased ferritin levels, despite small sample size and low adherence rate, whereas oral iron supplementation resulted in unchanged (n = 4) or decreased (n = 1) ferritin levels. CONCLUSIONS: Proactive and personalized micronutrient repletion schedules may decrease the risk of preoperative and early postoperative deficiency.