A number of diarylpyrazolylquinoline derivatives were synthesized and evaluated for their anti-dengue virus (DENV) activity. Among them, 6-fluoro-2-(1-(4-fluorophenyl)-3- (4-methoxyphenyl)-1H-pyrazol-5-yl)quinoline (11c), 2-[1,3-bis(4-methoxyphenyl)-1H-pyrazol- 5-yl]-6-fluoroquinoline (12c), and 4-[5-(6-fluoroquinolin-2-yl)-3-(4-methoxyphenyl)-1H-pyrazol- 1-yl]benzenesulfonamide (13c) exhibited approximately 10-folds more active anti-DENV-2 activity (IC50 of 1.36, 1.09 and 0.81 μM, respectively) than that of ribavirin (IC50 = 12.61 μM). Compound 13c was also potent inhibited other sero-types of DENV. It reduced DENV replication in both viral protein and mRNA levels, and no significant cell cytotoxicity was detected, with greater than 50% viability of Huh-7-DV-Fluc cells at a concentration of 200 μM. Furthermore, compound 13c can effectively protect mice from DENV infection by reducing disease symptoms and mortality of DENV-infected mice. It represents a potential antiviral agent to block DENV replication in vitro and in vivo. Structural optimization of the initial lead compound, 13c, and the detailed molecular mechanism of action are ongoing.