Docetaxel (DTX) is favoured option for breast cancer treatment; however its marketed formulation (Taxotere) generates therapeutic response at the cost of undue toxicity. In order to circumvent such limitations, DTX nanocrystals (DTX-NCs) were prepared through high pressure homogenization (HPH) technique using pluronic F-127 (PF-127) as a stabilizer. DTX-NCs presented higher efficacy against MCF-7 breast cancer cells with exposition of 1.75 and 2.13 fold lower inhibitory concentration (IC50) compared to free drug and Taxotere, respectively. DTX-NCs enhanced the DTX induce G2-M arrest by 1.24 and 1.79 fold compared to Taxotere and free DTX whereas highest apoptotic population (54.79%) of MCF-7 cells was also observed when cells were incubated with DTX-NCs for 24 h in comparison to free DTX (9.69%) and Taxotere (12.55%). The claims of improvement were substantiated by investigating the modulation in apoptotic mechanism induced by the subtle physical state variation of DTX in DTX-NCs. Results revealed that DTX-NCs induced apoptosis was linked to altered mitochondrial membrane potential. DTX-NCs caused highest (39.53%) depolarization of mitochondria compared to free DTX (9.34%) and Taxotere (18.72%). Further, safety of DTX-NCs was ascertained via haemolytic testing and in-vivo toxicity studies in mice. Developed formulation exhibited acceptable haemolytic potential which suggested its suitability towards parenteral administration. Moreover, in-vivo acute toxicity studies demonstrated that the developed NCs were safer than marketed Taxotere. These results elicit that DTX-NCs would be a viable alternative to commercial formulation for treatment of breast cancer.