A photo‐cross‐linked micelle is synthesized via photodimerization of thymine moieties fabricated from amphiphilic block copolymers (mPEG‐b‐P(LA‐co‐MPT). The crosslinking behavior is monitored by UV‐Vis spectra and 1H NMR. Dynamic light scattering (DLS) and transmission electron microscopy (TEM) showed that cross‐linked micelles had smaller sizes than their uncross‐linked precursors. In vitro studies reveal that cross‐linking of the micelle cores results in a slow drug release and faster cellular uptake in comparison with uncross‐linked ones in MCF‐7 and Hela cells. Moreover, the paclitaxel (PTX)‐loaded core‐cross‐linked micelles exhibit similar anticancer efficacy as free PTX. This work provides a convenient tool for designing a more stable structure in the blood circulation to realize a controlled drug delivery.