The management of cancer often involves therapeutic techniques that are frequently associated with drug tolerance or multidrug resistance. The effectiveness of plant secondary metabolites in fighting cancer can be significantly increased by synthesizing them at the nanometric scale. Moronic acid (MA) is a type of pentacyclic triterpenoid that hinders the regulation of cell growth, hence reducing the multiplication of cancer cells. Tamoxifen (TAM) is a supplementary compound used in the hormonal treatment of cancer, particularly breast cancer. In this study, we used the oil in oil (O/O) emulsion solvent evaporation method to synthesize Dammar gum nanoparticles (MTDNPs) loaded with MA and TAM. This was done to enhance the bioavailability and synergism of the nanoparticles. The zeta potential of MTDNPs was determined to be +23 mV, indicating the nanoformulations relative stability. The encapsulation efficiency values were determined to be 72.5% for MA and 76.6% for TAM. The MTDNPs exhibit a particle size ranging from 45 to 55 nm, as observed using transmission electron microscopy. The MTDNPs exhibited a continuous release pattern, and their antioxidant and anticancer capabilities were significantly stronger compared to the individual MA and TAM particles in their free form. The in vitro tests revealed that the combination of MA and TAM, encapsulated in dammar gum, exhibited a stronger inhibitory effect on the growth of A-549, MCF-7, and Hela cell lines compared to the individual administration of MA and TAM. This finding confirms the potent anticancer properties of the encapsulated compounds.