We presented a novel nanoformulation of atorvastatin (ATV), a statin with potential in the treatment of various tumors, including glioblastoma. A moderate increase in the apparent aqueous solubility of ATV by a factor of 100 was achieved, but the sizes of the formed particles are too large for intravenous administration at the highest drug loading. Only at low drug loading < 10 wt.%, nanoformulations (D h < 50 nm) were obtained while at higher loading, large submicron particles were formed. The encapsulated ATV was fully bioactive and exhibited IC 50 values in the low to medium micromolar range in a panel of different glioblastoma cell lines with no systematic difference between free, DMSO solubilized ATV and ATV solubilized using polymer micelles. In contrast, in tumor spheroids prepared from CT-2A mouse glioma and bRiTS-G2 mouse glioma cancer stem cells, the micellar formulation was consistently more active. Very interestingly, we found particularly high activity against bRiTS-G2 with minimal cell survival even at low micromolar ATV concentrations. Finally, transport through a blood-brain-barrier in vitro model based on differentiated human induced pluripotent stem cells was tested and revealed similar transport of micellar ATV and ATV dissolved by DMSO. However, as our novel micellar ATV formulations may enable much higher serum concentration of ATV, therapeutic doses may still be possible. Especially by combination with other active agents, micellar ATV may have potential for the treatment of glioblastoma.