Several strategies have been implemented to enhance brain drug delivery, and herein solid lipid nanoparticles functionalized with apolipoprotein E were tested in hCMEC/D3 cell monolayers. The mean diameter of 160 nm, negative charge of -12 mV, and their lipophilic characteristics make these nanosystems suitable for brain delivery. Confocal images and flow cytometry data showed a cellular uptake increase of 1.8-fold for SLN-Palmitate-ApoE and 1.9-fold for SLN-DSPE-ApoE when compared with the non-functionalized SLNs. Clathrin-mediated endocytosis was distinguished as the preferential internalization pathway involved in cellular uptake and nanoparticles could cross the blood-brain barrier predominantly by a transcellular pathway. The understanding of the mechanisms involved in the transport of these nanosystems through the blood-brain barrier may potentiate their application on brain drug delivery.