Overexpression of ATP binding cassette (ABC) transporters, including P-glycoprotein (P-gp) and breast cancer resistance protein (BCRP), is an important factor leading to multidrug resistance (MDR) in cancer treatments. Three subclasses of dual inhibitors of P-gp and BCRP were designed based on the active moieties of BCRP inhibitors, tyrosine kinase inhibitors, and P-gp inhibitors, of which compound <b>21</b> possessed low cytotoxicity, high reversal potency, and good lipid distribution coefficient. <b>21</b> also increased the accumulation of Adriamycin (ADM) and Mitoxantrone (MX), blocked Rh123 efflux, and made no change in the protein expression of P-gp and BCRP. Importantly, coadministration of <b>21</b> can significantly improve the oral bioavailability of paclitaxel (PTX). It was also demonstrated that <b>21</b> significantly inhibited the growth of K562/A02 xenograft tumors by increasing the sensitivity of ADM <i>in vivo</i>. In summary, <b>21</b> has the potential to overcome MDR caused by P-gp and BCRP and to improve the oral bioavailability of PTX.