Purpose: To describe the prevalence of perceptions of patients receiving a mismatch in treatment intensity, as perceived by intensive care unit (ICU) healthcare providers, and to assess the congruence of perceptions between providers. Methods: In this cross-sectional, observational study conducted in 21 ICUs in Australia and New Zealand, patient prevalence data was linked to an ICU staff survey to describe the extent to which patient treatment intensity was matched to the perceived prognosis and patient wishes. Results: Of the 307 study patients, 62 (20.2%) were reported to be receiving a mismatch in treatment intensity by at least one ICU healthcare professional. For reported mismatch, there was consensus amongst staff members for 52/62 (84%) of patients. Patients were significantly more likely to receive mismatched treatments if they were more severely unwell (APACHE II score > 20 vs. ≤ 20), odds ratio OR 2.35, 95% confidence interval (CI) 1.63–3.37, p < 0.0001, if they were an emergency admission (OR 3.05, CI 1.18–7.89, p = 0.0212) or if they had an advance care directive (OR 3.68, 95% CI 1.66–8.16, p = 0.0013). Conclusions: Being more severely unwell, being an emergency admission or having an advance care directive made patients more likely to be perceived as having a mismatch between the intensity of treatments provided and either the achievable goals of care, expected prognosis or patient’s wishes.