The present work describes the syntheses of diverse triazole bridged flavonoid dimers and identifies potent, nontoxic, and highly selective BCRP inhibitors. A homodimer, <b>Ac22(Az8)</b><sub><b>2</b></sub>, with <i>m</i>-methoxycarbonylbenzyloxy substitution at C-3 of the flavone moieties and a <i>bis-</i>triazole-containing linker (21 atoms between the two flavones) showed low toxicity (IC<sub>50</sub> toward L929, 3T3, and HFF-1 > 100 μM), potent BCRP-inhibitory activity (EC<sub>50</sub> = 1-2 nM), and high BCRP selectivity (BCRP selectivity over MRP1 and P-gp > 455-909). <b>Ac22(Az8)</b><sub><b>2</b></sub> inhibits BCRP-ATPase activity, blocks the drug efflux activity of BCRP, elevates the intracellular drug accumulation, and finally restores the drug sensitivity of BCRP-overexpressing cells. It does not down-regulate the surface BCRP protein expression to enhance the drug retention. Therefore, <b>Ac22(Az8)</b><sub><b>2</b></sub> and similar flavonoid dimers appear to be promising candidates for further development into combination therapy to overcome MDR cancers with BCRP overexpression.