Background: Older patients often have iron deficiency anemia before surgery, which can be effectively treated with intravenous iron supplementation (IVIS). Anemia and blood transfusions are associated with an increased risk of delirium. The aim of this research was to assess the effectiveness and safety of using IVIS in a prehabilitation program. Material and methods: Patients ≥70 y who underwent abdominal surgery between November 2015 and June 2018 were included in this single-center prospective cohort study. All patients were prehabilitated; however, only anemic patients received a single dose of 1000 mg intravenous iron (ferric carboxymaltose) to increase preoperative hemoglobin levels (IVIS group). Nonanemic patients received standard care (SC). The hemoglobin levels (primary outcome) were assessed at the outpatient clinic visit, at admission, and at discharge. Secondary outcomes were postoperative delirium, postoperative anemia, blood transfusion, complications other than delirium, and length of hospital stay. All outcomes were compared between the IVIS group and SC group. Results: Of all patients (n = 248), 97 anemic patients received IVIS (39%). Of the anemic patients, 50 patients (52%) had iron deficiency. Initial differences in hemoglobin concentrations between the IVIS group and SC group at T1 and T2 (7.2 versus 8.8; P < 0.001 and 7.4 versus 8.6; P = 0.023, respectively) were no longer present at discharge (6.6 versus 7.2; P = 0.35). No statistically significant differences were observed for all secondary outcomes between the IVIS group and the SC group. No infusion-related adverse events occurred. Conclusions: Adding IVIS to prehabilitation programs is safe and diminishes differences in these concentrations between preoperatively anemic and nonanemic patients. IVIS may be worthwhile as an additional component of prehabilitation programs. Results merit further investigation.