<p>Multi-stimuli-responsive polymers that exhibit temperature- and external stimulus-dependent phase transitions have attracted considerable interest as smart materials, whereas the development of multi-stimuli-responsive homopolymers remains challenging because of synthetic limitations in integrating multiple functional groups into well-defined repeating units. Herein, we report a multi-stimuli-responsive sulfur-containing <i>N</i>-alkylated nylon homopolymer incorporating redox-responsive disulfide groups and hydrophilic ether linkages into the polymer main chain. By tuning the hydrophilic–hydrophobic balance of the repeating unit structure, the homopolymer exhibited lower critical solution temperature (LCST)-type thermoresponsive behavior in water at ambient temperature. Systematic comparison of <i>N</i>-alkylated nylons bearing different functional groups revealed that disulfide groups serve as hydrophobic units within the polymer chains, clarifying their influence on hydration structures and phase-transition behavior. The polymer also demonstrated stimuli-induced multi-degradability, in which acid-catalyzed hydrolysis of amide bonds and reductive cleavage of disulfide bonds proceeded independently. Partial reduction induced controlled main-chain scission and oligomerization, resulting in enhanced aqueous solubility and a pronounced shift of the LCST-type cloud point to above 90 °C. These results demonstrate that redox stimuli can effectively regulate the thermoresponsive behavior. Owing to the high flexibility of main-chain molecular design, <i>N</i>-alkylated nylons provide a promising platform for the rational design of multi-stimuli-responsive homopolymers with tunable phase transition properties.</p>