Background Renal interstitial fibrosis is a critical symptom of chronic kidney disease (CKD) that is associated with high incidence. Extracellular vesicles produced by bone marrow mesenchymal stem cells (BMSC-EVs) can play important roles in the repair of injured tissues. However, no reports have investigated the role and mechanism of BMSC-EVs in renal fibrosis. Thus, we hypothesized that BMSC-EVs containing milk fat globule-EGF factor-8 (MFG-E8) could attenuate renal fibrosis by inhibiting the RhoA/ROCK pathway.Methods We investigated whether BMSC-EVs have antifibrotic effects in a rat model of renal fibrosis-rats subjected to unilateral ureteral obstruction (UUO) - as well as in cultured HK2 cells. In vivo, Sprague-Dawley (SD) rats were randomly divided into 6 groups: Sham group, Sham + EVs group, UUO group, UUO + EVs group, UUO + EVs Ctrl group, and UUO + EVs shMFGE8 group. In vitro, extracellular vesicles from BMSCs were collected and co-cultured with HK2 cells during transforming growth factor-β1 (TGF-β1) treatment. Besides, HK2 cells co-cultured with TGF-β1 were also treated with the ROCK inhibitor, Y-27632. Results Compared with the Sham group, UUO rats displayed fibrotic abnormalities, accompanied by increased expression of α-SMA and Fibronectin, and decreased expression of E-cadherin. Both molecular and pathological changes suggested an increased inflammation in damaged kidneys. Oxidative stress, as evidenced by decreased levels of SOD1 and Catalase, was also observed in UUO kidneys. In addition, activation of cleaved caspase-3 and PARP1 and increased apoptosis in the proximal tubules confirmed tubular cell apoptosis in the UUO group. All of these phenotypes exhibited by UUO rats were suppressed by treatment with BMSC-EVs. However, the protective effect of BMSC-EVs was completely abolished by inhibition of MFG-E8. Consistent with the in vivo results, treatment with BMSC-EVs reduced inflammation, oxidative stress, apoptosis, and fibrosis in HK-2 cells stimulated with TGF-β1 in vitro . Interestingly, treatment with Y-27632, a ROCK inhibitor, protected HK-2 cells against inflammation and fibrosis, although oxidative stress and apoptosis were unchanged. Conclusions In summary, our results show that BMSC-EVs containing MFG-E8 attenuate renal fibrosis, partly through RhoA/ROCK pathway inhibition.