A series of samarium ions (Sm3+) activated barium sodium niobate (Ba2NaNb5O15) samples have been successfully synthesized via employing a solid‐state reaction technique. Single phase, crystalline tetragonal Ba2NaNb5O15 were formed and the crystallite size of the prepared sample varied with doping of Sm3+ ions. The scanning electron microscopy (SEM) images of Ba2NaNb5O15:Sm3+ illustrate that the particles possess a non‐uniform spherical structure with some agglomeration. The prepared Ba2NaNb5O15:Sm3+ phosphors were efficiently excited with near‐ultraviolet (n‐UV) (406 nm) and emit strong visible emission peaks in the range 550–725 nm. The phenomenon of concentration quenching was detected after x = 0.10 mol of Sm3+ ions concentration for Ba2NaNb5O15, which arises due to non‐radiative energy transfer through dipole–dipole interaction among activator ions. Colour coordinates (0.586, 0.412) for the optimized phosphor lies in the visible reddish orange region. A bi‐exponential decay behaviour was observed for the photoluminescence decay curve of the optimized phosphor sample with an average decay time in milliseconds. The temperature dependent emission intensity confirms that the Ba2−xNaNb5O15:xSm3+ (x = 0.10 mol) phosphor exhibits adequate thermal stability having high value of activation energy (ΔE = 0.201 eV). The comprehensive study and analysis of the as‐prepared samples suggest that the intense reddish orange emitting thermally stable Ba2NaNb5O15:Sm3+ phosphor can act as a potential luminescent material in phosphor coated lighting, solar cells and other photonic devices.