A new quinazoline functionalized benzimidazole-based fluorogenic chemosensor H3L is synthesized and fully characterized by conventional techniques including single crystal X-ray analysis. It acts as a highly selective colorimetric and fluorescence sensor for Cu(2+) ions in DMF/0.02 M HEPES (1 : 1, v/v, pH = 7.4) medium. Reaction of H3L with CuCl2 forms a mononuclear copper(ii) [Cu(Cl)(H2L)(H2O)] (H2L-Cu(2+)) complex which is characterized by conventional techniques and quantum chemical calculations. Electronic absorption and fluorescence titration studies of H3L with different metal cations show a distinctive recognition only towards Cu(2+) ions even in the presence of other commonly coexisting ions such as Li(+), Na(+), K(+), Mg(2+), Ca(2+), Fe(2+), Fe(3+), Mn(2+), Co(2+), Ni(2+), Zn(2+), Cd(2+) and Hg(2+). Moreover, H2L-Cu(2+) acts as a metal based highly selective and sensitive chemosensor for S(2-) ions even in the presence of other commonly coexisting anions such as F(-), Cl(-), Br(-), I(-), SO4(2-), SCN(-), AcO(-), H2PO4(-), PO4(3-), NO3(-), ClO4(-), NO2(-), HSO4(-), HSO4(2-), S2O3(2-), S2O8(2-), CN(-), CO3(2-) and HCO3(-) in DMF/0.02 M HEPES (1 : 1, v/v, pH = 7.4) medium. Quantification analysis indicates that these receptors, H3L and H2L-Cu(2+), can detect the presence of Cu(2+) and S(2-) ions at very low concentrations of 1.6 × 10(-9) M and 5.2 × 10(-6) M, respectively. The propensity of H3L as a bio-imaging fluorescent probe for detection of Cu(2+) ions and sequential detection of S(2-) ions by H2L-Cu(2+) in Dalton lymphoma (DL) cancer cells is also shown.