Carboxylated functionalized multiwall carbon nanotubes (FMWCNTs) were prepared via nitric acid treatment. Decoration of FMWCNTs side walls with silver nanoparticles (AgNPs) was performed by mixing in silver nitrate (AgNO$_3$) solution giving FMWCNTs-Ag. Poly(vinyl chloride) (PVC) nanocomposites based on both pristine MWCNTs and its decorated form FMWCNTs-Ag in various contents (i.e., 0.5, 1.0, 3.0 and 5.0 wt%) were prepared in tetrahydrofuran solution followed by film casting. The obtained nanocomposites were specified by X-ray diffraction (XRD), transmission electron microscope (TEM), Raman spectroscopy, dynamic mechanical analysis (DMA), thermal analysis and dielectric properties measurements. The bacterial inhibition of the prepared film samples was also tested against Gram-positive (i.e., Bacillus subtilis and Staphylococcus aureus) and Gram-negative bacteria (i.e., Escherichia coli and Pseudomonas aeruginosa). The data were explained in according with filler type and loading. XRD analysis confirmed the homogeneous dispersion of FCNTs-Ag in PVC matrix. TEM showed that large number of AgNPs were anchored to FCNTs surface. This was confirmed by Raman spectra. DMA illustrated that with increasing FCNTs-Ag content up to 5.0 wt%, higher storage and loss moduli as well as smaller tan ${\delta}$ values with shifting to higher $T_g$ were obtained in comparison to composites with pristine CNTs. Thermogravimetric analysis indicated that increasing CNTs and FCNTs-Ag contents in PVC matrix up to 5.0 wt% improved PVC thermal stability. Differential thermogravimetric analysis showed a delay in PVC degradation rate on the initial step for composites based on FCNTs-Ag. Dielectric properties measurements illustrated that PVC composites with FCNTs-Ag exhibited higher electrical conductivity as compared with those based on pristine CNTs, but with the same order of magnitude (10$^{-8}$ ${\Omega}^{-1}$ cm$^{-1}$). This indicates that the prepared composite films can be applicable as electrostatic dissipated materials as the range of such application is 10$^{-9}$ to 10$^{-5}$ ${\Omega}^{-1}$ cm$^{-1}$. They also showed bacterial inhibition against the tested bacteria. This promises a potential use of the nanocomposites in medical fields as antimicrobial agents for the treatment of bacterial infection.