Cancer development and chronic diseases are associated with the overexpression of sialoglycans terminated to the surface proteins and lipids of cancer cells compared with normal cells. The isolation and detection of sialoglycopeptides from complex peptides mixture still remain challenges due to their low abundance, low ionization, and losses of sialic acid residues and water molecule during analytical processes. In this study, kapok fiber, a natural fiber derived from the kapok tree (Bombax ceiba L.), has shown excellent capability to specifically and efficiently enrich sialoglycopeptides, without losses of sialic acid residues and water molecule from sialoglycans. The main components on the surface of kapok fiber are syringyl and guaiacyl lignins which play an important role in isolating sialoglycopeptides from complex peptide mixtures.