This study explores the aldose reductase (AR) inhibitory potential of dinaphthodiospyrol H, a compound isolated from Diospyros kaki (Japanese persimmon). Aldose reductase plays a crucial role in the polyol pathway, a key factor in the progression of diabetic complications such as neuropathy and retinopathy. The isolated compound demonstrated the maximum AR inhibitory effect followed by the tested extract such as 87.34% and 49.09%, respectively. The AR inhibitory effect was supported by molecular docking studies highlighting its strong binding affinity to the AR active site. Complementary Density Functional Theory (DFT) analysis further elucidated the compound’s electronic properties, confirming its stability and effectiveness as an AR inhibitor. Docking studies carried out on the 3D crystallographic structure of Aldose Reductase; ALR2 (PDB ID = 2FZB) showed significant hydrophilic interactions with amino acid residues Ala299, Leu301, Ser302 and hydrophobic interactions with the Trp219. The findings suggest that dinaphthodiospyrol-H holds significant promise as a lead compound for developing novel therapeutic agents targeting diabetic complications through AR inhibition.