Eight previously undescribed lanostane triterpenoids, ganodeweberiols A ∼ H (1–8), together with eighteen known compounds (9–26), were isolated from the fruiting bodies of Ganoderma weberianum. The structures and absolute configurations of the new compounds were determined by extensive spectroscopic analysis, as well as NMR chemical shifts and electronic circular dichroism (ECD) calculations. Compounds 2, 7, 12, and 14 showed significant α-glucosidase inhibitory activity with IC₅₀ values ranging from 35.3 μM ∼ 223.4 μM compared to the positive control acarbose (IC₅₀, 304.6 μM). Kinetic study indicated that the most potent compound 12 was a mixed type inhibitor for α-glucosidase. Molecular docking simulation revealed the interactions of 12 with α-glucosidase. Additionally, Compounds 3 and 6 inhibited glucagon-induced hepatic glucose production in HepG2 cells with EC₅₀ values of 42.0 and 85.9 μM, respectively. Further study revealed that compounds 3 and 6 inhibited hepatic glucose production by suppression glucagon-induced cAMP accumulation. Moreover, compounds 3 and 26 were active against HeLa cell line with IC₅₀ values of 17.0 and 6.8 μM, respectively.