ABSTRACT This paper focuses on the investigation of null controllability in the context of stochastic controlled relaxed systems with one control, aiming to establish several equivalent conditions for this property. More precisely, by the classical duality analysis, we present the equivalence between an observability inequality for the backward stochastic system associated with the relaxed system and null controllability. Furthermore, we characterize the null controllability through a minimal norm control problem, employing a constructed quadratic functional and leveraging a variational characterization of its minimizer. Finally, we provide an application of our findings and extend the analysis to relaxed systems with two controls.