Polyamidoamine dendrimer (PAMAM) is a class of synthetic macromolecular polymers for targeted drug delivery. PAMAM dendrimers are characterized by a pure defined structure, adjustable nanoscale dimensions, mono-dispersity, and versatile surface modification. The objective of this study was to study the covalent coupling of methotrexate (MTX) to PAMAM dendrimer, which was loaded with the natural product anticancer agent, berberine (BER) for the targeting of HeLa cells. The successful preparation of MTX-conjugated PAMAM loaded with BER (MTX-PAMAM-BER) was confirmed by Fourier transform infrared spectroscopy and particle size was evaluated using dynamic light scattering. The biological assays, MTT, flow cytometry, ROS levels evaluation and DAPI staining were used to assess the cytotoxicity effect of the prepared nanosystem. The findings indicated that MTX-PAMAM-BER exhibited greater suppression of tumor cell growth in comparison to BER, MTX, PAMAM-BER, and MTX-PAMAM. Besides, the noteworthy ROS level has been seen in the treated cells with MTX-PAMAM-BER. Finally, it should be stated that the fabricated MTX-PAMAM-BER co-delivery nanosystem could be a promising agent for cancer therapy and targeting.