Drug resistance of cancer cells is a major issue in cancer treatment. Plant-mediated nanoparticle synthesis has been applied in recent years to overcome this problem. In this study, the biogenic synthesis of AuNPs was explored using Satureja rechingeri Jamzad aqueous leaf extract, and their anticancer effects were evaluated in cisplatin-resistant A2780CP ovarian cancer cells. The chemical composition of S. rechingeri Jamzad was analyzed using gas chromatography-mass spectrometry. The characteristics of green-synthesized AuNPs were confirmed using XRD, FTIR, UV-visible spectroscopy, TEM, SEM, EDX, DLS, and zeta potential. The cytotoxic effects of AuNPs and S. rechingeri Jamzad aqueous extract on cisplatin-resistant A2780CP ovarian cancer cells were evaluated by MTT assay and flow cytometry. Real-time PCR analyzed gene expression. The chemical composition revealed that carvacrol (89%) was the main component of the S. rechingeri Jamzad extract. The average size of the spherical biosynthesized AuNPs was 15.1 ± 3.7 nm. The AuNPs and plant extract inhibited the growth of cisplatin-resistant ovarian cancer cells in a time- and dose-dependent manner. The apoptotic cell death was confirmed by flow cytometry and DAPI staining. The proapoptotic genes were upregulated, while anti-apoptotic and metastatic genes were downregulated. According to the cell cycle analysis, cancer cells were arrested in the G0/G1 phase. Considering the anticancer activity of the synthesized AuNPs using S. rechingeri Jamzad and the low side effects of AuNPs on normal cells, these AuNPs showed strong potential for use as biological agents in drug-resistant cancer cells treatment.