Purpose <p>Resection of glioblastomas infiltrating the motor cortex and corticospinal tract (CST) is often linked to increased perioperative morbidity. Navigated transcranial magnetic stimulation (nTMS) motor mapping has been advocated to increase patient safety in these cases. The additional impact of patient frailty on overall outcome after resection of cases with increased risk for postoperative motor deficits as identified with nTMS needs to be investigated.</p> Methods <p>Patients with newly diagnosed motor eloquent glioblastomas were retrospectively evaluated. Patients underwent nTMS- and tractography-based neuronavigation. Demographic, imaging- and nTMS-derived data and the 11-item modified frailty index (mFI-11) were collected. Primary endpoint was discharge home after tumor resection. A 4-item score comprising preoperative motor deficit, mFI-11 ≥ 2 points, distance to the CST &lt; 12&#xa0;mm and infiltration of nTMS-positive cortex was established to predict overall outcome.</p> Results <p><i>N</i> = 64 patients with a mean age of 64.8 ± 9.6 years (60.9% male) were included. 46 patients (71.9%) could be discharged to their homes. Risk factors for non-home discharge were greater mFI-11 (<i>p</i> = 0.027), surgery-related motor deficit (<i>p</i> &lt; 0.001) and overall complications (<i>p</i> &lt; 0.001 for non-surgical and <i>p</i> = 0.006 for surgical complications). In multiple regression analyses, mFI-11 and surgery-related deficit were statistically robust. The 4-item score predicted non-home discharge with an AUC = 0.745, 95%CI = 0.62–0.87, <i>p</i> &lt; 0.001.</p> Conclusion <p>In patients with newly diagnosed motor-eloquent glioblastomas, nTMS-based planning helps to predict postoperative surgery-related motor deficits. Patient frailty needs to be respected in decision making in addition to nTMS- and tractography-based planning in order to avoid postsurgical motor deficits and to keep overall surgical morbidity on a low level.</p>