Background: Real-time ultrasound-guided catheterization of the internal jugular vein (IJV) is widely used for its safety and high success rate. However, it becomes difficult when the IJV’s cross-sectional area (CSA) is reduced. A reported technique applies manual pressure (with fingers) to the supraclavicular IJV to impede venous return and enlarge the distal CSA. While effective in previous studies, its clinical utility remains unclear, as those studies involved only healthy volunteers and used blind technique. Therefore, this study aimed to evaluate the efficacy of our novel ultrasound-guided compression of the proximal IJV. Methods: In this prospective observational study, 25 hospitalized patients were included. Two ultrasound machines were used: one to visualize the CSA of the distal IJV, and the other to apply and guide compression of the supraclavicular IJV, ensuring real-time confirmation of venous occlusion. Patients were asked about pain during the compression procedure. The primary outcome was the degree of dilation at the puncture site of the IJV. Results: All 25 patients (mean Sequential Organ Failure Assessment score: 5.2±3.6) completed the study. Supraclavicular IJV compression resulted in a significant increase in the CSA of the distal IJV by approximately 150%, from 0.4±0.3 cm² to 1.0±0.3 cm² (P<0.001). No patient reported any pain during the procedure. Conclusions Ultrasound-guided supraclavicular IJV compression significantly increased the CSA of the distal IJV in hospitalized patients. This method enhances vein visibility by increasing IJV volume, potentially improving the success and safety of central venous catheterization.