Aim Myeloid differentiation factor 88 (MyD88) plays a key role in tumor proliferation and metastasis. Targeting MyD88 is a potent strategy in tumor therapy. TJ-M2010-5 is a small molecule derivative of aminothiazole and could inhibit dimer formation of MyD88. To explore the potential of TJ-M2010-5 in tumor therapy, we determined its antitumor effect and correlate mechanisms of TJ-M2010-5 in hepatocellular carcinoma (HCC). Methods The antitumor effect of intratumoral injection of TJ-M2010-5 to H22 tumor-bearing BALB/c mice was observed. Tumor growth was monitored. The expression of MyD88 and Ki-67 were detected by immunofluorescence. In vitro, the impacts of TJ-M2010-5 on proliferation, cell cycle, necrosis, and apoptosis of H22 cells were evaluated. The direct and indirect effects of TJ-M2010-5 on macrophages were evaluated using flow cytometry. Results TJ-M2010-5 induced both G(0)/G(1) and G(1)/S phase arrests in HCC cells. Mechanically, downstream activation of MyD88 was suppressed by TJ-M2010-5 through the extracellular regulated protein kinase-1/2/p90 ribosomal S6 kinase/glycogen synthase kinase-3 beta signaling pathway. In turn, cyclin-dependent kinase (CDK)6/cyclin D1 and CDK2/cyclin E complexes were downregulated. More importantly, TJ-M2010-5 significantly inhibited tumor growth in mice. Additionally, the portion of antitumor M1 macrophages (F4/80(+)CD11c(+)) in the tumor microenvironment were increased after TJ-M2010-5 treatment. Together, these data indicate that TJ-M2010-5 is a promising therapeutic drug for HCC. Conclusions These results indicate that MyD88 is a feasible target for antitumor treatment and TJ-M2010-5 is a qualified candidate for HCC therapy.