Traumatic brain injury (TBI) is significant, from a public health standpoint, because it is a major cause of the morbidity and mortality of young people. Cerebral edema after a TBI, if untreated, can lead to devastating damage of the remaining tissue. The current therapies of severe TBI (sTBI), as outlined by the Brain Trauma Foundation, are often ineffective, thus a new method for the treatment of sTBI is necessary. Herein, the reduction of cerebral edema, after TBI, using an osmotic transport device (OTD) was evaluated. Controlled cortical impact (CCI) was performed on adult female CD-1 mice, and cerebral edema was allowed to form for 3 h, followed by 2 h of treatment. The treatment groups were craniectomy only, craniectomy with a hydrogel, OTD without bovine serum albumin (BSA), and OTD. After CCI, brain water content was significantly higher for animals treated with a craniectomy only, craniectomy with a hydrogel, and OTD without BSA, compared to that of control animals. However, when TBI animals were treated with an OTD, brain water content was not significantly higher than that of controls. Further, brain water content of TBI animals treated with an OTD was significantly reduced, compared to that of untreated TBI animals, TBI animals treated with a craniectomy and a hydrogel, and TBI animals treated with an OTD without BSA. Here, we demonstrate the successful reduction of cerebral edema, as determined by brain water content, after TBI using an OTD. These results demonstrate proof of principle for direct water extraction from edematous brain tissue by direct osmotherapy using an OTD.