Delirium is the sudden alteration of the state of consciousness and perception, fluctuating over hours or days. It predominates in older adults and is associated with the aging process. The incidence of delirium increases between 10% and 15% in surgical interventions. The objective of this study was the design and validation of a nursing care plan for elderly patients with postoperative delirium. This study was based on the Delphi method and applied to nursing professionals at the Hospital Universitario del Caribe, Cartagena. The sample consisted of 36 nurses with knowledge of the taxonomy of nursing diagnoses. The care plan was applied in two rounds. For the analysis, measures of central tendency and dispersion were used, as well as frequency and percentages. The participants were women (90.9%) from the hospitalization service (51.5%), with training in Nursing Diagnosis (NANDA), Nursing interventions classification (NIC) and Nursing Outcome Classifications (NOC) (78.8%). The validated care plan has eight diagnostic features. Highlights include “Risk for Ineffective Cerebral Tissue Perfusion” and “Disturbed Sleep Pattern” (in 98.1%; 11 results), with the highest score in the first round being “Vital Signs” (with 100%) and “Sleep” (100%) and “Mobility” (100%) in the second round. Forty-four interventions and 18 suggested activities were identified. This care plan offers the nursing professionals reliable and pertinent tools in clinical practice for the management of patients with postoperative delirium.