The role of catalysts in the development of improved bleaching methods is of paramount scientific and industrial importance in the bleaching of raw cotton and laundry stains. Despite tremendous efforts, developing novel earth abundant metal nanocatalysts with high activity and stability remains a great challenge. Here, we demonstrate the successful formation of earth abundant transition metal-chelated layer-by-layer hyaluronic acid/chitosan polyelectrolyte-coated mesoporous silica nanoparticles (Metal@PEM-MSNPs) as novel bleaching nanocatalysts. Metal@PEM-MSNPs have been tested for both the oxidative degradation of a natural plant dye in solution and tea- and beetroot- stains on cotton fabrics. While manganese and iron-chelated PEM-MSNPs (Mn2+@PEM-MSNPs and Fe2+@PEM-MSNPs) have little catalytic activity, cobalt-chelated PEM-MSNPs (Co2+@PEM-MSNPs) display an unexpected, surprisingly high activity in the oxidation reaction under the same experimental conditions. The results suggest that Co2+@PEM-MSNPs are excellent nanocatalytic systems for the low temperature bleaching (<30 C-0) and the design strategy used in Metal@PEM-MSNP nanocatalysts can further be extended to prepare a wide range of highly active self-assembled bio-inspired nanocatalysts for catalytic bleaching and other organic transformations.