Intensive care units (ICUs) are emotionally demanding workplaces. Exposure to stress can negatively impact ICU staff members' emotional resilience, health, and capacity to provide care. Despite recognition of the benefits of promoting "healthy workplaces", there are limited interventional studies aimed at improving the well-being of ICU staff.The aim of this study was to assess the effectiveness of a multifaceted intervention for improving well-being of staff working in a tertiary ICU.A before-and-after interventional study was conducted over a 2-year period, between 2019 and 2021. Interventions included social activities, fitness, nutrition, and emotional support. An electronic version of the PERMA-Profiler questionnaire was used to assess the well-being of a convenience sample of ICU staff before (n = 96) and after (n = 137) the intervention. Ten focus groups (each involving 12-18 nurses) were held to explore nurses' perceptions of the intervention's effectiveness.After the intervention, a significantly greater proportion of participants described their work week as draining (32% vs 19%, χAfter the intervention, there was a preserved level of well-being from baseline despite a statistically significant increase in staff reporting the work week as draining and at least a little bit harder than normal. These findings must be considered in light of the COVID-19 pandemic, which started after baseline data collection and continues to impact the community, including staff workload and pressures in intensive care. The study findings may inform strategies for improving ICU staff members' well-being.