Healthcare professionals often face ethical conflicts and challenges related to decision-making that have necessitated consideration of the use of conscientious objection (CO). No current guidelines exist within Spain’s healthcare system regarding acceptable rationales for CO, the appropriate application of CO, or practical means to support healthcare professionals who wish to become conscientious objectors. As such, a procedural framework is needed that not only assures the appropriate use of CO by healthcare professionals but also demonstrates its ethical validity, legislative compliance through protection of moral freedoms and patients’ rights to receive health care. Our proposal consists of prerequisites of eligibility for CO (individual reference, specific clinical context, ethical justification, assurance of non-discrimination, professional consistency, attitude of mutual respect, assurance of patient rights and safety) and a procedural process (notification and preparation, documentation and confidentiality, evaluation of prerequisites, non-abandonment, transparency, allowance for unforeseen objection, compensatory responsibilities, access to guidance and/or consultative advice, and organizational guarantee of professional substitution). We illustrate the real-world utility of the proposed framework through a case discussion in which our guidelines are applied.