The weaning procedure is complex and depends on an adequate assessment to identify the moment of progression and continuity. Lung and diaphragmatic ultrasound are valuable tools for analyzing various variables such as lung aeration, areas of collapse, presence of fluid, and decreased diaphragmatic muscle strength and mobility, among others. Ultrasound measurements can be static or dynamic, and over the years, it has presented different protocols and standards for each pathological condition, with reference values. Currently, it is possible to quantify physiological changes using this tool and carry out precise and continuous assessment and monitoring at the patient’s bedside, in a practical, fast, and easily accessible way. It is essential to guarantee the safety and efficiency of ventilator weaning in critically ill patients, and lung and diaphragm ultrasound will help to reduce complications and bring about successful weaning with the best outcomes.