Currently, cancer treatments are highly invasive, and they have been associated with a lot of adverse effects that put patient integrity at risk. Therefore, research of novel molecules and delivery systems capable of achieving a therapeutic effect that modifies inhibits and reduces the proliferative activity in cancer cells and, at the same time, reduce adverse effects associated with conventional therapies is imperative. In this study, we analyzed the biological effect of a novel cinnamic acid derivative, 3,4-dichlorobencil-p-phenoxylcilamide, in polymeric nanoparticles over MCF–7 breast cancer cells. The nanoparticulated system showed an inhibitory influence over cellular metabolism at equal or higher concentrations than 25 μM of 3,4-dichlorobencil-p-phenoxylcilamide, which is associated with PPARγ transcriptional activity, in addition to the decrease in the proliferation antigen Ki-67 basal levels. Those results position this kind of nanoscale system as an alternative on breast cancer treatment and lay the basis for research on the action mechanism associated with its cellular metabolism modulation and relationship with another hallmark on breast cancer cellular models.