Background: Peripherally inserted central venous catheters (PICC) are widely used in patients with haematological malignancies owing to the requirement for prolonged intravenous therapy. However, the growing use of PICCs has resulted in a multitude of complications such as infections and thrombosis, leading to prolonged hospitalisation periods and increased morbidity. This study aimed to determine the incidence of and factors associated with PICC-related complications in patients with haematological malignancies. Methods: This prospective cohort study was conducted at a single academic institution. The inclusion criteria involved all adult patients with haematological malignancies who had newly inserted PICCs. The patients were observed for a minimum duration of 60 days to evaluate the incidence of PICC-related infections and thrombosis, as well as mechanical complications. Results: A total of 119 PICCs were implanted in 85 patients. Among them, more than half of the patients were diagnosed with lymphoma (55.0%). The median dwell time was 61 days (interquartile range: 98 days). The incidence of PICC-related complications was 58.0% (6.9 per 1,000 catheter-days). Specifically, 43 PICCs (36.1%, 4.3 per 1,000 catheter-days) experienced infective complications, 25 (21.1%, 2.5 per 1,000 catheter-days) encountered mechanical complications and 1 (0.8%, 0.1 per 1,000 catheter-days) exhibited thrombotic complications. Furthermore, an underlying diagnosis of acute leukaemia was significantly associated with a higher incidence of PICC-related infections. Conclusion: Our study revealed higher incidence rates of PICC-related complications in adult patients with haematological malignancies compared to the finding of other studies. Notably, patients with underlying acute leukaemia displayed a higher incidence of PICC-related infections. These findings underscore the importance of implementing appropriate interventions and conducting thorough root cause analyses to effectively mitigate this complication and improve patient outcomes.