This study introduces a sustainable and multifunctional textile dyeing approach using carboxymethyl cellulose (CMC) syn
thesized from agricultural waste—peanut shell and rice straw—in combination with natural dyes extracted from peanut red
skin (PRS), red onion peel (ROP), and henna (HE). Cotton and polyester fabrics were pre-treated with CMC (0.5–1.5%) and
crosslinked to enhance dye–fiber interactions, followed by dyeing under various controlled conditions. The influence of key
parameters, including pH, temperature, dyeing time, and polymer concentration, was systematically investigated to optimize
color uptake and fixation behavior. Results showed that rice-straw-derived CMC, owing to its higher degree of substitution
and superior film-forming characteristics, produced significantly higher color strength (K/S) values than peanut-shell CMC
on both textile substrates. Optimal dyeing was achieved at pH 5–7, 70–80 °C, and 60–90 min, yielding uniformly dyed
fabrics with excellent washing (4–5), rubbing (3–5), and light fastness (3–5). The treated fabrics also exhibited remarkable
functional enhancements, including improved tensile properties, ultraviolet protection (UPF 40–50), and substantial antimi
crobial activity (up to 91% reduction against E. coli, S. aureus, and C. albicans). Henna and PRS extracts were most effective
in imparting bioactive performance, while CMC significantly enhanced dye retention and surface reactivity. The proposed
mechanism suggests that coloration results from synergistic hydrogen bonding, polymer entrapment, and crosslink-stabilized
dye–polymer–fiber networks. Overall, this work demonstrates an eco-friendly, circular, and high-performance natural dyeing
technology that transforms agricultural residues into value-added biopolymers and functional pigments suitable for sustain
able textile finishing.