Five undescribed abietane diterpenoids, along with eight known analogs, were isolated from Phlegmariurus carinatus. Their structures were unambiguously elucidated by extensive analysis of spectroscopic data and comparison between the literature. The absolute configuration of phlecarinatone C was determined by evaluating ECD spectra. Four undescribed abietane diterpenoids and eight known analogs were tested for their neuroprotective and cytotoxic activities, separately. Teuvincenone C showed potential neuroprotective effect against Hemin-induced HT22 cell damage. Importantly, phlecarinatone C showed pronounced cytotoxic effect against U251 cells in vitro assays. The biological evaluation revealed that phlecarinatone C could inhibit proliferation, migration, and invasion in a concentration-dependent manner of U251 cells. Meanwhile, phlecarinatone C effectively reversed epithelial-to-mesenchymal transition (EMT) and promoted U251 cells apoptosis via a mitochondrial apoptotic pathway. Taken together, phlecarinatone C might be a valuable candidate for anti-metastatic agents against glioblastoma treatment.