This paper presents a detailed experimental investigation aimed at comprehensively studying the mixing and screech tone characteristics of a rectangular jet subjected to fluidic injection. The primary objective is to analyze the influence of varying the mass flow rate ratio (Cm) between the fluidic injector and the main jet, as well as the expansion ratio (Pe/Pa) of the main jet, on the screech tone phenomena and mixing behavior of the jet. Extensive acoustic measurements are conducted to assess the impact of different flow conditions on screech noise generation. Additionally, pitot measurements are performed to investigate the variations in jet pressure profiles, providing crucial information regarding the jet’s dynamic features and the effectiveness of fluidic injection in reducing the core length of the jet, (L∗). Schlieren flow visualization techniques are employed to study the evolution of the jet’s shock structures and reveal the underlying flow physics. The experimental results demonstrate that the mass flow rate ratio (Cm) plays a vital role in governing the screech tone characteristics, with distinct frequency and amplitude variations observed for different Cm values. Moreover, the expansion ratio (Pe/Pa) significantly affects the screech tone frequency and exhibits a direct correlation with the jet’s shock cell structure. The findings contribute valuable insights into the screech tone phenomenon and its dependency on key flow parameters.