We conducted validation of a scale to measure nursing workloads, previously designed using NIC interventions within the four nursing functions (patient care, teaching, management, and research). Methods: This is an analytical, descriptive, prospective, and observational study using qualitative methodology (focus groups and in-depth interviews) with a quantitative and qualitative section (committee of experts and real application of the scale through a validation pilot and with multicentric application, including hospitalization units of internal medicine and surgery of four hospitals). Qualitative analysis was performed with Atlas.ti8 and quantitative analysis with R. Results: Qualitatively, all the participants agreed on the need to measure workloads in all nursing functions with standardized terminology. The expert committee found greater relevance (91.67%) in “prevention” and “health education” as well as consistency with the construct and adequate wording in 99% of the selected items. In the pilot test and multicenter application, the nurses spent more time on the caring dimension, in the morning shift, and on the items “self-care”, “medication”, “health education”, “care of invasive procedures”, “wounds care”, “comfort”, and “fluid therapy”. Cronbach’s alpha 0.727, composite reliability 0.685, AVE 0.099, and omega coefficient 0.704 were all acceptable. Construct validity: KMO 0.5 and Bartlett’s test were significant. Conclusions: The scale can be considered valid to measure nursing workloads, both qualitatively in obtaining the consensus of experts and health personnel and quantitatively, with acceptable reliability and validity superior to other similar scales.