<p>In this study, micro-nanofibrillated cellulose (MNFC) was prepared using an environmentally friendly approach. Specifically, bamboo pulp was pretreated through high-consistency mechano-enzymatic fibrillation, followed by high-speed blending and dispersion, resulting in MNFC with a diameter of 9.77 ± 3.83&#xa0;nm and a water retention capacity of up to 1207%. The prepared MNFC was utilized as a reinforcing material for poly(acrylic acid-acryloylamino-2-methyl-1-propanesulfonic acid) P(AA-AMPS) hydrogels, aiming to enhance their mechanical properties and water absorption capacity. The effects of incorporating high-content MNFC on the mechanical and water absorption properties of the hydrogels were investigated. The results demonstrated that, compared to hydrogels without MNFC, the addition of MNFC led to a more uniform material structure, with the hydrogel fully recovering its original shape after 80% compressive deformation. The incorporation of 5% MNFC increased the compressive stress strength of the P(AA-AMPS) hydrogel by tenfold, while the addition of 15% MNFC improved the water absorption rate by 68% and the initial water retention capacity by 3.4&#xa0;times. More importantly, compared to traditional low consistency nanocellulose production methods, the MNFC preparation method in this study is more environmentally friendly and efficient, offering a cost-effective alternative. The introduction of high-content MNFC not only increases the proportion of biomass materials in the hydrogel, reducing reliance on petroleum-based materials, but also constructs a robust network structure, significantly enhancing the mechanical strength and water absorption performance of the hydrogel. These P(AA-AMPS) hydrogels, reinforced with high-content MNFC and exhibiting excellent mechanical properties and ultra-high water absorption capacity, show great potential for applications in agriculture, hygiene, and the food industry.</p> Graphical abstract <p></p>