Display omitted •A dual responsive colorimetric and fluorescent turn-on sensor DN for Fe3+ was synthesized.•Simple sensor DN towards Fe3+ exhibited excellent selectivity, high sensitivity and fast response (20 s).•The detection limit of Fe3+ was calculated as low as 0.178 μM.•Sensor DN was successfully used for detecting Fe3+ in water and food samples as well as test strips. A new dual responsive colorimetric and fluorescent turn-on sensor DN for Fe3+ based on Schiff base derivative was designed and synthesized by one-step reaction. The sensor DN exhibited highly selective, sensitive and fast recognition toward Fe3+ with distinct color change by naked eyes in DMSO/H2O (1:1, v/v) solution over other competitive metal ions. The interaction of DN with Fe3+ caused a significant enhancement in emission intensity due to the restricted C = N isomerization and the suppression of highly efficient photoinduced electron transfer (PET) process. The sensing complex DN-Fe3+ was well-characterized to be 1:2 by the Job’s plot, 1H NMR titration, FTIR, HR ESI-MS analysis and DFT studies. The detection limit of DN for Fe3+ was as low as 0.178 μM, which displayed high sensitivity towards Fe3+. The sensor DN-based filter paper strips can be used to conveniently and effectively detect Fe3+ ions by the naked eyes. Importantly, the sensor DN was further used for detecting Fe3+ in real water and food samples with acceptable results and good recoveries.