Textile industry is a major water consumer and generates complex and highly toxic effluents. Conventional biological treatment methods often fail to achieve effective remediation due to the high recalcitrant pollutant loads. Additionally, these processes produce large volumes of sewage sludge (SS) containing harmful contaminants, which require proper management strategies to mitigate environmental impact and promote resource recovery. Anaerobic digestion (AD) is a promising, but slow process for wastewater and SS treatment; however it can be accelerated by supplementing carbon materials, which facilitate electron transfer. This study evaluated the AD potential for treating a textile effluent (TE), cellulosic textile residues (TR), and SS from a textile wastewater treatment plant. Prior to biodegradation assays, assessment of TE’s impact on the acetoclastic community revealed a 29% inhibition of specific methanogenic activity (SMA) at 0.5 gCOD/L, which was counteracted by activated carbon (AC), restoring and stimulating SMA. TE showed low biodegradability, however, supplementation with volatile fatty acids increased methane production (MP) to (715 ± 4) LCH4/kg of volatile solids (VS) of inoculum. AC enhanced MP rates by 20% while achieving 60% decolorization. SS also exhibited low biochemical methane potential (BMP), with only ~ 20% of its organic matter converted to CH4. In contrast, TR demonstrated high BMP, achieving complete organic matter conversion into CH4 with MP comparable to the cellulose control (399 ± 15 LCH4/kgVS). Co-digestion at 80:20%VS (SS/TR), yielded MP similar to that of individual residues, suggesting that TR enhances anaerobic process stability by compensating SS's slower degradation and improving overall digestion efficiency.