Three unreported dammarane-type triterpenoids with rare skeletons (1–3), along with one undescribed gypenoside (4), were isolated from the aerial parts of Gynostemma pentaphyllum using diverse chromatographic materials and pre-HPLC. Their structures were elucidated on the basis of spectroscopic and spectrometric data, while the absolute configurations of 1–3 were assessed via electronic circular dichroism (ECD) analyses. Notably, compounds 1–3 possess a 3,19-hemiketal bridge in the A ring. Saponin 4 possesses an unreported 20,25-oxa structural moiety. Their antiproliferative effects against HepG2, MCF-7, and DU145 cell lines were screened. Compounds 1–3 displayed moderate cytotoxicity with IC50 values ranging from 13.7 ± 0.2 to 32.0 ± 1.7 μM.