Administrative jurisprudence and judiciary considered the application of the principle of non-retroactivity of administrative decisions a justification for preserving stable rights and legal positions, as the public interest dictates that individuals should not lose confidence and security regarding the stability of their rights and legal positions that have been previously settled under the application of former legal systems, except based on a law or a judicial ruling that permits retroactivity. This study employed an analytical approach to examine legal texts and judicial principles concerning the non-retroactivity of administrative decisions, and utilized a comparative method to analyze the legal systems of Oman, Egypt, and Jordan. It revealed the perspectives of legal scholars and established judicial rulings on the concept and justifications of this principle. It also explored the stance of legal doctrine and administrative judiciary in the studied countries regarding the consequences of violating this principle. Additionally, the study delved into the concept of retroactive effect of administrative decisions, its conditions, and analyzed appointment decisions as a practical application of retroactivity in the Sultanate of Oman, and it clarified in its latter half the exceptions to the principle of non-retroactivity of administrative decisions, concerning legislative provisions permitting retroactivity, or based on the nature or necessity of administrative decisions. It addressed retroactivity based on the administration's authority to revoke its decisions, as well as judicial revocation through annulment judgments. The study concluded that the principle of non-retroactivity of administrative decisions is a constitutional principle and one of the most important general principles of law. The judiciary in the studied countries embraced the broad jurisprudential concept of this principle, as well as the modern theory of the retroactive effect. Additionally, legal security reinforces the principle of non-retroactivity of administrative decisions by instilling a sense of reassurance among stakeholders that their acquired rights and legal positions will not be compromised. The study concluded with, it suggested the establishment of a specialized judicial body for legal opinions, legislature refrain from including retroactivity except within narrow limits and primarily for the benefit of individuals. Additionally, it suggested including transitional provisions in any law or regulation project. Lastly, it proposed amending the Omani Official Gazette Law to include the publication of laws, regulations, and decisions using modern technological means for accessibility by individuals.