INTRODUCTION: Due to advances in critical care medicine, more patients survive their critical illness. However, intensive care unit (ICU) survivors often experience long-term physical, cognitive and mental problems, summarised as post-intensive care syndrome (PICS), impacting their health-related quality of life (HRQoL). In what frequency PICS occurs, and to what extent this influences ICU survivors' HRQoL, is mostly unknown. The aims of this study are therefore to study the: (1) 5-year patient outcomes, (2) predictors for PICS, (3) ratio between HRQoL of ICU survivors and healthcare-related costs, and (4) care and support needs. METHODS: The MONITOR-IC study is a multicentre prospective controlled cohort study, carried out in ICUs in four Dutch hospitals. Patients will be included between July 2016 and July 2021 and followed for 5 years. We estimated to include 12000 ICU patients. Outcomes are the HRQoL, physical, cognitive and mental symptoms, ICU survivors' care and support needs, healthcare use and related costs. A control cohort of otherwise seriously ill patients will be assembled to compare long-term patient-reported outcomes. We will use a mixed methods design, including questionnaires, medical data from patient records, cost data from health insurance companies and interviews with patients and family members. ETHICS AND DISSEMINATION: Insights from this study will be used to inform ICU patients and their family members about long-term consequences of ICU care, and to develop prediction and screening instruments to detect patients at risk for PICS. Subsequently, tailored interventions can be developed and implemented to prevent and mitigate long-term consequences. Additionally, insights into the ratio between HRQoL of ICU patients and related healthcare costs during 5 years after ICU admission can be used to discuss the added value of ICU care from a community perspective. The study has been approved by the research ethics committee of the Radboud University Medical Center (2016-2724). CLINICAL TRIAL REGISTRATION: NCT03246334.