miR-200c-3p is aberrantly expressed in numerous cancers, but its underlying mechanisms in nephroblastoma are unknown. In our study, the differentially regulated miRNAs between the nephroblastoma tissues and adjacent non-neoplastic renal tissues were screened based on microarray analysis. The miR-200c-3p expression in nephroblastoma tissues and cells was detected by qRT-PCR. Then, the effects of miR-200c-3p mimic or inhibitor on cell proliferation, invasion, and migration were evaluated by CCK-8 assay, plate colony formation assay, soft agar assay, Transwell, and wound-healing assay in SK-NEP-1 and G401 cells. Afterward, the target gene of miR-200c-3p was predicted by TarBase, miRTarBase, miRDB softwares, and then verified by dual-luciferase reporter gene assay. The in vivo effects of miR-200c-3p on pathological changes and tumor volume were investigated in tumor xenograft mice by H&E staining and in vivo fluorescence imaging. ChIP assay was used to evaluate the relationship between histone acetyltransferase E1A-binding protein p300 (EP300) and P27, and the relationship of the role of miR-200c-3p in nephroblastoma and the AKT/FOXO1/p27 signaling pathways was evaluated by western blotting. Our study shows that miR-200c-3p was downregulated in nephroblastoma tissues and cells, and EP300 was a target gene of miR-200c-3p. Furthermore, miR-200c-3p mimic decreased cell proliferation and inhibited cell migration and invasion in nephroblastoma. Mechanistically, miR-200c-3p could inhibit p-AKT activity and enhance p-FOXO1 and p27 expression. Notably, the transcription factor P27 could bind to the EP300 promoter. This study demonstrates a new approach to treat nephroblastoma.