Context: Galbanic acid (GBA) is a sesquiterpene coumarin with different medicinal properties and anticancer effects. Objective: To improve the anticancer activities of GBA, in the current study, we aimed to fabricate GBA-loaded solid lipid nanoparticles (GBA-SLNs) and study their biological activities in vitro. Materials and methods: Hot homogenization was used for preparation of GBA-SLNs. The encapsulation efficiency (EE) and drug loading (DL) and in vitro release were determined. MTT, DAPI, DNA fragmentation, comet, and Anexin V apoptosis assays were used to compare the anti-cell proliferation and genotoxicity properties of GBA and GBA-SLNs against A549 cells and HUVEC to detect apoptosis and DNA damage in the final concentration of 100 mM after 48 h treatment. Results: Scanning electron microscopy (SEM) and particle size analysis showed spherical SLNs (92 nm), monodispersed distribution, and zeta potential of À23.39 mV. High EE (498%) and long-term in vitro release were achieved. The stability of GBA-SLNs in aqueous medium was approved after 3 months in terms of size and polydispersity index. GBA was able to inhibit A549 growth with an IC 50 value of 62 mM at 48 h. Although GBA-SLNs could also inhibit the growth rate of A549 cells, the effect is perceived after 48 h, as approved by the quantitative expression of Bcl-xL and Casp 9 genes, and also genotoxicity assays. Conclusion: Long-term apoptotic effect of GBA-SLNs compared with GBA may be due to the accumulation of GBA-SLNs in the tumor site because of deviant tumor pathology. Our data confirmed that SLNs could be exploited for sustained lipophilic GBA delivery.