<p>This study reports the green synthesis of copper oxide (CuO) thin films using parsley (<i>Petroselinum crispum</i>) plant extract, followed by dip-coating deposition to investigate their structural, optical, and electrical properties. CuO nanoparticles were subsequently used to prepare homogeneous dip solutions for thin-film fabrication. Glass substrates coated with CuO films at 10 and 20 deposition cycles were annealed at 450 °C to enhance crystallinity. XRD confirmed the monoclinic CuO phase with nanoscale crystallite sizes (60–70 nm). SEM analysis revealed an average particle size of approximately 80 nm for the seed layer, while increasing the deposition cycles produced denser, smoother, and more compact thin films with reduced porosity. EDX analysis confirmed the chemical purity and uniform Cu–O stoichiometry of the films. UV–Vis spectroscopy showed strong absorption peaks at 350 and 360 nm, and the optical band gap decreased from 2.6 eV (10 cycles) to 2.3 eV (20 cycles), respectively, due to enhanced crystallinity and film thickness. FTIR confirmed Cu–O bond formation with the residual organic functional groups originating from the plant extract. Electrical properties strongly depend on the number of deposition cycles. 10-cycle films exhibited higher resistivity (4.5 × 10⁻¹ Ω·cm) and moderate carrier density (2.1 × 10¹⁸ cm⁻³), whereas 20-cycle films showed markedly lower resistivity (1.09 × 10⁻¹ Ω·cm) and higher carrier concentration (1.19 × 10¹⁹ cm⁻³). The results demonstrate that optimizing deposition cycles improves structure ordering, charge transport, and light absorption. The green-synthesized CuO thin films exhibit significant potential as absorber layers and hole-transport materials in environmentally sustainable solar cell designs.</p>