In this work we present results of theoretical and experimental investigation of the optical absorption spectra of thin films of nanocomposite materials composed of silver nanoparticles embedded in a diamond-like carbon (DLC) matrix. The optical characteristics of DLC-Ag nanocomposite are considered within the framework of the effective medium approximation. The evolution of plasmon resonance characteristics and optical properties due to changes of dielectric constant of DLC host and size of the embedded metal nanoparticles is studied. The experimental absorption spectra of DLC-based silver nanocomposites deposited by reactive magnetron sputtering on fused-silica were compared with the simulated ones. The observed redshift and broadening of the surface plasmon resonance (SPR) bands were explained using Mie scattering theory and Maxwell–Garnett effective medium theory. The obtained results suggest that a random mixture consisting of the DLC film with embedded isolated silver inclusions is a promising material for the fabrication of tunable nanocomposites in different sensing platforms.