The aerospace industry has seen a significant push to develop shorter and more aerodynamically “aggressive” intermediate compressor ducts (ICDs) due to their potential to reduce engine weight and, consequently, overall specific fuel consumption. However, many aggressive designs tend to either experience flow separation or operate close to their separation limit. This study investigates the use of circumferential splitter vanes as a passive flow control device to suppress flow separations and enhance the aerodynamic robustness of these ducts. The test case examined is a state-of-the-art, highly aggressive ICD developed by the Institute of Propulsion Technology at the German Aerospace Center (DLR). This ICD operates near its separation limit at its nominal operating point. Numerical simulations were employed to assess the aerodynamic performance of both the baseline and augmented (splittered) ICD designs. Analysis of the baseline design revealed a strong tendency for flow separation at the hub-strut corner, mid-strut region, and in the shroud region near the duct’s exit plane. The introduction of a double splitter vane in the augmented designs was found to be effective in reducing flow separation in the hub and shroud regions. Nevertheless, the potential benefits must be balanced against the resulting increase in overall total pressure losses, indicating a need for further optimization of the splitter vane design.