Surface modification of metal oxide nanomaterials is one of the promising techniques for tailoring its optoelectronic properties. In this paper, a novel method has been reported for controlling the optical band gap, generation of trapping states and inhibiting the charge carrier’s recombination rate in TiO2 nanocrystals (NCs). It has been achieved through the surface modification of TiO2 NCs using organic ligands such as formamide (FA) and polyethylene glycol (PEG). Investigations reveal that the luminescence properties have also been tuned exhibiting efficient visible light-harvesting photocatalytic activity. All these have been attributed to the interaction between ligands (PEG) and TiO2 forming deep electronic states associated to C-C and C-O bonds which facilitate blue and green wavelength emissions. On the other hand, FA plays an important role as capping ligand and nitriding agent generating shallow and deep trapping states endowed with visible emission at higher wavelength. Furthermore, nitrogen doped functionalized TiO2 NCs (N-TiO2) using urea are prepared solvothermally at temperature as low as 150 °C and pressure higher than 1 atm. Under that conditions, well defined N-TiO2 anatase phase NCs show a band gap of 2.3 eV and exhibit slow electron hole recombination which have been discussed with an emphasis in view of surface modification.