Background: Open-heart surgery is associated with life-threatening complications, and providing nonstandard nursing care without any plan for patients undergoing this type of surgery in the intensive care unit (ICU) can deteriorate their conditions. Objectives: This study investigated the effect of providing nursing care based on Gordon's functional health patterns model on the clinical outcomes of patients undergoing coronary artery bypass surgery in the cardiac surgery ICU. Methods: This was a quasi-experimental study involving 58 patients undergoing coronary artery bypass surgery admitted to the cardiac surgery ICU of Ahvaz Golestan Hospital in 2021. The patients were selected using convenience sampling and based on the inclusion criteria, and they were divided into intervention and control groups. First, the information related to the outcomes of the patients in the control group was collected using a checklist. Then, all the ICU nurses working at the study site were trained in Gordon's model and how to perform nursing care based on this model. They provided the necessary nursing care based on this model for the patients in the intervention group under the supervision of the researcher. The data of the patients in the intervention group were collected after completion of the intervention using the same checklist used for the control group. Finally, the data were analyzed using SPSS version 25. Results: There was a statistically significant difference between the intervention and control groups in the length of stay at the ICU (P = 0.007), length of ventilation (P = 0.001), and successful weaning from the ventilator (P = 0.026). However, there was no significant difference between the 2 groups in terms of patient mortality (P = 0.16) or re-admission to the ICU (P = 0.16). Conclusions: According to the results, Gordon's functional health patterns model of the nursing process can be easily used to improve the care and treatment outcomes of patients admitted to the cardiac surgery ICU.