Background: The treatment of anemia in patients with cardiorenal syndrome (CRS) is based mainly on intravenous (IV) iron therapy and/or erythropoiesis-stimulating agents (ESAs). There are concerns about the safety of ESAs due to a potentially higher risk for stroke and malignancy. Objective: We aimed to explore whether IV iron alone is sufficient to improve anemia in CRS patients and to define the predictors of treatment response. Methods: We retrospectively analyzed data of 81 CRS patient treated for anemia at our clinic. All patients received IV iron for 6 weeks. A subset of patients was additionally given subcutaneous ESAs. The end point was the improvement from baseline in hemoglobin (Hb) and ferritin levels at week 7. Results: We retrieved the files of 81 patients; 34 received IV iron alone and 47 were given IV iron and ESAs (the combination group). The Hb levels significantly increased in both groups (in the IV iron alone group: 10.6 ± 1.1 to 11.9 ±1.1 g/dl, p < 0.001; in the combination group: 10.2 ± 0.9 to 12.4 ± 1.3 g/dl, p < 0.001), but more pronouncedly in the combination group (2.17 vs. 1.24 g/dl; p = 0.001). The platelet count decreased significantly in the IV iron alone group but was unchanged in the combination group. Eighty percent of patients attained a Hb target of 11 g/dl, with no significant difference between the two groups (73.5 vs. 85.1%; p = 0.197). Low baseline Hb was the only predictor of a favorable outcome to treatment. Conclusion: Our observational study suggests that IV iron treatment without ESAs may substantially raise the Hb level to ≥11 g/dl in CRS patients. This treatment strategy may reduce the use of ESAs and hence its potential adverse effects.