Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the efficacy of BA‐KING® Bacillus velezensis as a zootechnical feed additive to be used as a gut flora stabiliser for chickens for fattening, chickens reared for laying, turkeys for fattening, turkeys reared for breeding and all avian species for fattening or rearing to slaughter or point of lay including non‐food producing species. The product under assessment is based on viable spores of a strain identified as B. velezensis, which is considered suitable for the qualified presumption of safety (QPS) approach to safety assessment. In a previous opinion, the FEEDAP Panel concluded that BA‐KING® was safe for the target species, consumers of products derived from animals fed the additive and the environment. Additionally, the additive was not irritant to skin but potentially irritant to eyes and respiratory sensitiser. The Panel could not conclude on the efficacy of the additive for the target species at the proposed conditions of use. In the current application, two additional efficacy trials in chickens for fattening were provided. The results showed an improvement in the performance parameters of chickens when supplemented with BA‐KING® at 2.0 × 108 CFU/kg complete feed relative to a control group. Considering the previously submitted studies and the newly submitted studies in chickens for fattening, the Panel concluded that BA‐KING®, supplemented at 2.0 × 108 CFU/kg complete feed, has the potential to be efficacious in all avian species for fattening or reared for laying/breeding and non‐food‐producing avian species at the same physiological stage.