We have developed a dual-function drug carrier, polyethylene glycol (PEG)-derivatized farnesylthiosalicylate (FTS). Here we report that incorporation of a drug-interactive motif (Fmoc) into PEG(5k)-FTS2 led to further improvement in both drug loading capacity and formulation stability. Doxorubicin (DOX) formulated in PEG(5k)-Fmoc-FTS2 showed sustained release kinetics slower than those of DOX loaded in PEG(5k)-FTS2. The maximum tolerated dose of DOX- or paclitaxel (PTX)-loaded PEG(5k)-Fmoc-FTS2 was significantly higher than that of the free drug. Pharmacokinetics and biodistribution studies showed that DOX/PEG(5k)-Fmoc-FTS2 mixed micelles were able to retain DOX in the bloodstream for a significant amount of time and efficiently deliver the drug to tumor sites. More importantly, drug (DOX or PTX)-loaded PEG(5k)-Fmoc-FTS2 led to superior antitumor activity over other treatments including drugs formulated in PEG(5k)-FTS2 in breast cancer and prostate cancer models. Our improved dual function carrier with a built-in drug-interactive motif represents a simple and effective system for targeted delivery of anticancer agents.