Molecular pathways that contribute to orbital fibroblast activation during thyroid-eye disease (TED) may promote TED progression. Non-coding RNAs, especially miRNAs, play a critical role in the pathogenesis of TED. In the present study, miR-103a-3p was dramatically upregulated and TGFBR3 was downregulated within TED orbital tissue samples and TGF-β-stimulated TED orbital fibroblasts. miR-103a-3p inhibition in TGF-β-stimulated TED orbital fibroblasts partially abolished TGF-β-induced fibrotic alterations, as manifested by the impaired fibroblast cell viability and decreased vimentin and fibronectin levels. miR-103a-3p directly targeted TGFBR3 in TED orbital samples and TGF-β-stimulated TED orbital fibroblasts. In TGF-β-stimulated TED orbital fibroblasts, TGFBR3 overexpression inhibited fibroblast cell viability and decreased vimentin and fibronectin levels. TGFBR3 overexpression partially attenuated the inhibitory effects of miR-103a-3p overexpression on TGFBR3 expression and the promotive effects of miR-103a-3p overexpression on TGF-β-induced fibrotic alterations. Under TGF-β stimulation, miR-103a-3p overexpression significantly promoted, whereas TGFBR3 overexpression inhibited the phosphorylation of Erk1/2, JNK, Smad2, and Smad3. TGFBR3 overexpression also partially abolished the effects of miR-103a-3p overexpression on Erk1/2, JNK, Smad2, and Smad3 phosphorylation. In conclusion, the miR-103a-3p/TGFBR3 axis regulated TGF-β-induced TED orbital fibroblast activation and fibrosis in TED, with the possible involvement of the Erk/JNK and TGF-β/Smad signaling pathways.