The present research combines biosorption and photocatalysis in a functional TiO2-immobilized chitosan adsorbent (CTA). CTA can degrade organic pollutants and adsorb metal ions simultaneously. Target pollutants were dyes of cationic (rhodamine B, Rh.B) and anionic (methyl orange, MO) nature, with Ni2+ and Cu2+ selected as heavy metals. The presence of Ni2+ or Cu2+ improved the degradation ability of CTA for MO, but inhibited the degradation of Rh.B, with Cu2+ exhibiting stronger effects than Ni2+. There was no significant difference in CTA activity when the metal ions were pre-adsorbed or when they coexisted in the solution with the organic dyes. Protons in the reaction system affected the degradation performance in a similar way for Ni2+ and Cu2+ leading to a different effect on the degradation for MO and Rh.B. An X-ray photoelectron spectroscopy analysis of the binding energies of the metal ions on the surface in the presence of the cationic or anionic dyes explained the different behaviors. Since anionic and cationic dyes possess chromogenic groups of different charges, they adversely affect the production of OHaEuro cent radicals when coexisting with Cu2+ or Ni2+.