Abstract Objective To evaluate the impact of subcutaneous tunneling on peripherally inserted central catheters (PICCs) dislodgement and malposition. Dislodged or malpositioned PICCs can lead to improper treatment. The subcutaneous tunneling strategy may be effective, but there is insufficient evidence, and proximal movement has not been explored. Methods We randomized 630 patients who needed PICCs placement to either the tunneled PICCs (experimental group) or the nontunneled PICCs (control group). Dislodgement and malposition of the catheter were the primary outcomes, and catheter-related infection (CRI) and catheter-related thrombosis (CRT) were the secondary outcomes. Results Subcutaneous tunneling does not significantly reduce distal catheter movement, but it significantly reduces proximal catheter movement (4.3% vs. 9.9%, P = 0.007), which may explain the lower incidence of CRI (2.0% vs. 5.3%, P = 0.030) and CRT (3.6% vs. 12.5%, P < 0.001). Conclusions Although subcutaneous tunneling does not significantly improve catheter prolapse, it should still be used clinically because proximal catheter movement can be a more serious problem associated with CRI and CRT.