Workplace stress, as experienced by nurses working in intensive care units, can affect health, quality and delivery of nursing care and healthcare costs. However, no studies have purely focused on Paediatric Intensive Care Units [PICU] and specifically considered workplace stress within a Saudi Arabian context. This study addressed this omission. This study explored workplace stress amongst nurses working in PICUs in Saudi Arabia. A mixed-method research was conducted in two phases. In Phase One, (n = 172) nurses from six PICUs completed a questionnaire; in Phase Two, face-to-face semi-structured interviews were conducted with 24 of the original 172 participants. The quantitative data revealed that workplace stress was associated with workload (2.29 ± 0.81), followed by death and dying (2.07 ± 0.77) alongside patients and their families (2.02 ± 0.79). Most nurses suffered from medium levels of workplace stress; this was associated with tangible personal characteristics, including nationality and academic nursing qualifications. Six key themes emerged from the qualitative results: Sources of workplace stress, consequences of workplace stress, individual characteristics that help to manage workplace stress, work characteristics that help to manage workplace stress, motivation to work in PICUs in Saudi Arabia and suggestions for workplace stress management. The Dynamic Model of Workplace Stress was developed, highlighting the interactions between the sources and consequences of workplace stress. Despite reporting a medium level of workplace stress, the nurses perceived their workplace to be a highly rewarding environment.