Cellulose was extracted from mango fibers and subjected to acid hydrolysis to obtain a nanofiber. Two morphological structures based on the polylactic acid (PLA)/nanocellulose (NC) combination have been synthesized and FeO NPs (M) are incorporated into both combinations. The first formulation is obtained by blending technique (PLA/M-NC) and the second formulation is obtained by self-assembly of grafted copolymer (M-PLA-co-NC). The magnetic nanocomposites are used as carriers for 5-fluorouracil (5-FU), an anti-cancer drug, and curcumin (CUR) to get PLA/M-NC/5-FU/CUR and M-PLA-co-NC/5-FU/CUR. The structural, morphological, and magnetic properties of the obtained nanocomposites were characterized by various techniques. The loading, release of 5-FU/CUR and the inhibition efficacy of nanocarriers loaded drugs against bacteria, HePG-2, MCF-7, and HCT-116 cell lines were studied. The two morphological forms of nanocarriers are considered close in loading % of 5-FU; however, the M-PLA-co-NC nanocarrier loaded double the loading % of CUR into PLA/M-NC nanocarrier, revealing superiority of copolymeric micelle than the blended formulation. The dual drugs loaded magnetic copolymeric micelles M-PLA-co-NC/5-FU/CUR revealed slower release, higher antibacterial and antitumor efficacy than the PLA/M-NC/5-FU/CUR. In this respect, the M-PLA-co-NC/5-FU/CUR could be considered a good nanomedicine against Streptococcus, Bacillus subtilis, Klebsiella pneumonia and Escherichia coli bacteria, besides the investigated cell lines.