<p>This study focuses on the effect of the&#xa0;supramolecular architecture of microcrystalline cellulose (MCC) on the adsorption of cationic and anionic dyes. Two different allomorphs of microcrystalline cellulose (I and II) were synthesized from the biomass residue, Kapok pod, and their physical and chemical characteristics were studied meticulously. FTIR Analysis indicates the changes in intensities and positions of absorption bands arising from the allomorphic transition. The XRD diffractograms revealed a higher crystallinity for MCC I than for MCC II. The surface morphology differed and disclosed a more porous structure for MCC II, as evident from the FE-SEM micrographs. The N₂ adsorption–desorption isotherms of the MCC allomorphs are analyzed to gather additional details about their porous structure. TGA–DTG analysis shows that MCC I is more thermally stable. The adsorption efficiency of MCC allomorphs, originating from the same precursor, toward the cationic dye Methylene Blue (MB) and the anionic dye Congo Red (CR) was determined. The Freundlich model befitted the MB dye adsorption on MCC I; in contrast, the Langmuir model showed the best fit for CR adsorption on MCC I. The Freundlich isotherms appropriately described the MB and CR adsorption on MCC II. The kinetic studies showed that the adsorption process followed the pseudo-second-order model. Molecular docking was conducted to elucidate the adsorption interactions of the representative dyes with MCC allomorphs. The present study demonstrated that the difference in the adsorption pattern of cellulose allomorph adsorbents toward cationic and anionic dyes is not merely due to electrostatic interactions but due to the synergistic effect of hydrogen bonding and van der Waals interactions. These findings contribute to a comprehensive understanding of dye adsorption on cellulose allomorphs, thereby harbingering for future research on the application of cellulose allomorphs in selective adsorption of dyes.</p>