Purpose: To identify modifiable and non-modifiable risk factors for peripheral intravenous catheter (PIV) failure among patients requiring intravenous treatment for oncology and haematology conditions. Methods: A single-centre prospective cohort study was conducted between October 2017 and February 2019. Adult in-patients requiring a PIV for therapy were prospectively recruited from two cancer units at a tertiary hospital in Queensland, Australia. The primary outcome was a composite of complications leading to PIV failure (local and bloodstream infection; occlusion; infiltration/extravasation; leakage; dislodgement; and/or phlebitis). Secondary outcomes were (i) PIV dwell time; (ii) insertion and (iii) failure of a CVAD; (iv) adverse events; (v) length of hospital stay. Outcomes were investigated using Bayesian multivariable linear regression modelling and survival analysis. Results: Of 200 participants, 396 PIVs were included. PIV failure incidence was 34.9%; the most common failure type was occlusion/infiltration (n = 74, 18.7%), then dislodgement (n = 33, 8.3%), and phlebitis (n = 30, 7.6%). While several patient and treatment risk factors were significant in univariable modelling, in the final multivariable model, only the use of non-sterile tape (external to the primary dressing) was significantly associated with decreased PIV dislodgement (hazard ratio 0.06, 95% confidence interval 0.01, 0.48; p = 0.008). Conclusion: PIV failure rates among patients receiving cancer treatment are high, the sequelae of which may include delayed treatment and infection. Larger studies on risk factors and interventions to prevent PIV failure in this population are needed; however, the use of secondary securements (such as non-sterile tape) to provide further securement to the primary PIV dressing is particularly important. Trial registration: Study methods were registered prospectively with the Australian New Zealand Clinical Trials Registry on the 27th March 2017 (ACTRN12617000438358); https://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=372191&isReview=true.