In this manuscript, a nickel acetate, Ni(AcO)(2), thin films incorporating MAPbBr(3) (MA: methylammonium) semiconductor perovskite nanocrystals is proposed as a suitable media to generate amplified spontaneous emission (ASE) and random lasing (RL). These nanocomposites are conveniently spin-coated onto SiO2/Si substrates, forming active planar waveguides. The thicknesses of the films are properly adjusted to exhibit single-mode propagation at the emission wavelength of the nanocrystals (530 nm) and high strong-mater interaction of the mode with the active region. Under a nanosecond pulsed excitation, fabricated structures exhibit the generation of amplified spontaneous emission (ASE), which is outcoupled from the edge of the sample. Moreover, the waveguide also exhibits narrow lasing lines (