Co-liquefaction is an emerging technology aimed at enhancing bio-oil yield and quality, compensating for decrease in feedstock, increasing productivity, and adding revenue to bio-refineries. This study delves into the influence of plastic waste (PW) types during co-liquefaction with cotton gin trash (CGT) on the yield and quality of the produced crude oil. Various plastics, including PLA (polylactic acid), PVA (polyvinyl alcohol), PET (polyethylene terephthalate), LDPE (low-density polyethylene), HDPE (high-density polyethylene), PP (polypropylene), and PS (polystyrene), were investigated in a mixing ratio of 2:1 (CGT/plastic waste) at 320 °C and 2 hours in supercritical ethanol (ScEtOH), without catalyst, to produce energy-dense bio-oil under optimised conditions. The study presents the suitability of different types of plastic waste for co-feeding with CGT, along with their synergistic and antagonistic effects on product fraction yield (oil, solid, and gas), and oil energy yield. High bio-oil yields of 54.5 wt%, 53.7 wt%, and 43.1 wt% were achieved during co-liquefaction of CGT with PLA, PET and PVA, respectively. Bio-oil with the highest Higher Heating Values (HHV) was achieved through the co-liquefaction of CGT with PVA (30.6 MJ/kg) and PS (31.5 MJ/kg). The solid fractions obtained from co-liquefying CGT with PLA and PVA contained 46.9 wt% and 55.1 wt% carbon, respectively, making them potential sustainable sources for soil amendment. Furthermore, the bio-oils were characterised using gas chromatography-mass spectroscopy (GC-MS), two-dimensional nuclear magnetic spectroscopy-heteronuclear single quantum coherence (2D‐NMR-HSQC), elemental analysis, fourier transform infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA) to assess their quality and stability. Solid residues were characterised to understand the extent of plastic degradation and their suitable applications. The results indicate that the co-liquefaction of lignocellulosic biomass with plastics represents a viable and promising approach for improving bio-oil quality and extending its shelf life.