The Choosing Wisely (CW) initiative provides recommendations for healthcare providers, aimed at reducing unnecessary or inappropriate tests and procedures. A clinical decision support (CDS) alert in the electronic health record was developed to reflect organizational CW guidelines regarding blood chemistry panel ordering in the primary care setting. An interrupted time series design was used to analyze the weekly proportion of inappropriate blood chemistry panel orders prior to and after implementation of the CDS alert in treatment and control groups. Implementation of the CDS alert significantly decreased the average weekly proportion of inappropriate blood chemistry panels from 28.64% to 15.69% in the treatment group (p < .001). Apart from other efforts implemented simultaneously to reduce inappropriate lab ordering, the CDS alert produced a significant reduction in inappropriate lab ordering. We conclude that CDS alerts can be an effective strategy for healthcare organizations seeking to more closely adhere to CW guidelines.