An effective combustion technique is used to synthesize Sr0.8La0.2Fe12-xCuxO19 (x = 0,1) M-type strontium hexagonal ferrite nanoparticles (SHFNPs). The impact of La and La-Cu substitution on the structural, microstructural, and magnetic characteristics of SHFNPs is scrutinized. The samples are characterized using several experimental techniques, such as X-ray diffraction (XRD), Raman spectroscopy (RS), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and vibrating sample magnetometer (VSM). The obtained results reveal that the single lattice structure of the substituted strontium hexaferrite can be acquired by transforming Fe3+ to Fe2+ on the 2a site. Raman spectroscopy (RS) verifies the formation of all crystallographic sites of hexaferrite. The broadening of 4f2 and 12k peaks indicates the presence of disorder at the crystal sites resulting from the change in the chemical environment after doping with Cu2+ ions. FESEM images reveal flat hexagonal facets of the particle that signify the magneto-plumbite structure. The magnetic results provide high values of both intrinsic coercivity and (BH)max. The obtained data constitute good magnetic characteristics for perpetual magnet applications. Furthermore, the reduced coercivity of the Sr0.8La0.2Fe11CuO19 (SLCHF) sample with high magnetizations can be used to create microwave absorbing and data storage materials.