MicroRNAs (miRNAs) play a critical role in the regulation of tumor metastasis. The role of these molecules in hepatocellular carcinoma (HCC), however, has not been fully elucidated. In this study, we employed miRNA-sequencing and identified 22 miRNAs involved in HCC metastasis. One of these, miR-28-5p, was downregulated in HCCs. This downregulation correlated with tumor metastasis, recurrence, and poor survival. Biofunctional investigations revealed that miR-28-5p deficiency promoted tumor growth and metastasis in nude mice without altering the in vitro biological characteristics of HCC cells. Through gene expression profiles and bioinformatics analysis, we identified interleukin-34 (IL-34) as a direct target of miR-28-5p, and the effects of miR-28-5p deficiency on HCC growth and metastasis was dependent on IL-34-mediated tumor-associated macrophage (TAMs) infiltration. Moreover, we found that TAMs induced by miR-28-5p-IL-34 signaling inhibit miR-28-5p expression on HCC cells via transforming growth factor-β1 (TGF-β1), resulting in an miR-28-5p-IL-34-macrophage positive feedback loop. In clinical HCC samples, miR-28-5p levels were inversely correlated with IL-34 expression and the number of TAMs. Patients with low miR-28-5p expression, high IL-34 levels, and high numbers of TAMs had a poor prognosis with shorter overall survival (OS) and time to recurrence (TTR). Conclusion: an miR-28-5p-IL-34-macrophage feedback loop modulates HCC metastasis and serves as a novel prognostic factor as well as a therapeutic target for HCC. This article is protected by copyright. All rights reserved.