•In situ synthesis of Ag NP-adorned guar gum functionalized Fe3O4 nanocomposite.•FE-SEM, TEM, EDS-elemental mapping, XRD, and ICP techniques used to assess the structural and physicochemical characteristics.•In the catalytic application the 4-nitrophenol (4-NP) was reduced over the Fe3O4@guar gum/Ag NPs as a nanocatalyst.•catalyst sustainability was assessed by its recyclable properties in seven further without significant degradation activity.•MTT assay used to evaluate bio-application of the nanocomposite for in vitro anticancer investigation againstAN3-CAendometrial cell lines. In situ synthesis of Ag nanoparticle-adorned guar gum functionalized Fe3O4 nanocomposite (Fe3O4@guar gum/Agnanocomposite) and its subsequent catalytic and biological uses are described in this research along with a sustainable approach for the process. FE-SEM, TEM, EDS-elemental mapping, XRD, and ICP were among the analytical techniques used to assess the structural and physicochemical characteristics of this unique material. In the catalytic application the reduction of 4-nitrophenol (4-NP) was carried out using freshly generated Fe3O4@guar gum/Ag NPs as a nanocatalyst. To monitor the reduction process, a UV–Vis spectrophotometer was utilized. We evaluated this catalyst's sustainability using its recyclable properties in seven further cycles and the findings indicated a consistent and significant degradation activity.Additionally, the MTT assay wasused to expand the bio-application of the nanocomposite for in vitro anticancer investigation againstAN3-CAendometrial cell lines. In presence of the material, the malignant endometrial cell line's cell survival decreased in a dose-dependent manner. The nanocomposite was shown to have IC50 values of 87 μg/mL when it cameto the AN3-CA cell line. Given the remarkable outcomes the created nanocomposite demonstrated, cancer management might look very promising in the near future. Display omitted