Polyvinylpyrrolidone (PVP)/cellulose acetate (CA) composite nanofibres loaded with Chromolaena odorata (L) King extract were prepared using the electrospinning method. The physicochemical properties of nanofibre composites, including their morphology, size, crystallinity, chemical interactions and compressive strength, were studied. In vitro tests including antioxidant, antibacterial and release activities were also investigated. The morphology of the nanofibre composites containing C. odorata extract (COE) had a smooth, homogeneous and flexible surface and fibres with a diameter of 1454 nm. Fourier-transform infrared spectroscopy analysis showed the interaction of PVP, CA and COE molecules through hydrogen bonds. The XRD pattern showed that crystals were transformed into the amorphous state when COE was converted into nanocomposite fibres. The Young's modulus values of the resulting nanofibre composites were in the range of 199–209 MPa. The antioxidant activity of PVP/CA nanocomposite fibres contained higher COE than did pure COE, whereas the antibacterial activity of PVP/CA/COE nanofibre was as strong as that of pure COE. The release rate of COE in nanofibres increases faster than does pure COE.