<p>This study investigates the rheological behavior of soft colloidal suspensions composed of chitin-derived microgels, carboxymethyl chitin (CMCH) and its sulfated derivative (CMCHS), dispersed in Newtonian (water) and non-Newtonian (hyaluronic acid, HA) fluids. Flow and oscillatory measurements clarify the dual influence of particle deformability and matrix viscoelasticity on macroscopic response. Sulfate groups reduces crosslinking density and elastic modulus, producing softer CMCHS microgels. In Newtonian media, both systems exhibit three flow regimes: dilute, soft glassy, and jammed, with CMCHS requiring higher concentrations to reach jamming due to greater deformability. The Wu–Morbidelli fractal model revealed that CMCHS formed more compact aggregates (<i>D</i>_<i>f</i> = 1.9) within a weak-link dominated network (<i>α</i> = 0.6), whereas CMCH formed looser aggregates (<i>D</i>_<i>f</i> = 1.75) with transition region between weak and strong connections (<i>α</i> = 0.51). In HA-based suspensions, viscoelastic confinement by entangled polymer chains produced compact intra-floc structures (<i>D</i>_<i>f</i> ≈ 2.1) but softer, polymer-mediated inter-floc junctions. The overall response was governed by the polymer network, which suppressed the dilute regime, induced an apparent yield stress, and reduced the sensitivity of elasticity to particle concentration. This dual control enables tunable rheology in soft colloidal systems, offering design principles for advanced biomedical, cosmetic, and industrial formulations.</p> Graphical abstract <p></p>