Judicial knowledge constitutes one of the most significant means of proving criminal offenses in Iran’s criminal justice system. Its foundations are rooted in Imamiyyah jurisprudence, particularly in the inherent authority of certainty, the necessity of discovering the truth, and the judge’s duty to administer justice. The Islamic Penal Code defines judicial knowledge as certainty derived from clear and demonstrable evidence. Nevertheless, ambiguity surrounding the concept of certainty, its distinction from strong suspicion and personal conviction, the limits of knowledge derived from circumstantial and scientific evidence, and the reviewability of judgments based on judicial knowledge may lead to the subjectivization of the standard of proof and inconsistent decisions in similar cases. Employing a descriptive-analytical method and a comparative approach, this study re-examines the jurisprudential foundations of judicial knowledge and evaluates the possibility of comparing it with the “beyond a reasonable doubt” standard under English law. The findings demonstrate that, despite their different origins, structures, and legal functions, judicial knowledge and the beyond-a-reasonable-doubt standard share fundamental features, including the requirement of rational conviction, the protection of the presumption of innocence, and the prevention of convictions based on suspicion or insufficient evidence. Moreover, the presumption of innocence, the rule of darʾ, the prohibition against adjudication based on conjecture, and the principle of caution in matters concerning life, sexual integrity, and reputation provide sufficient jurisprudential grounds for restricting the judge’s personal knowledge and functionally adopting the requirement to eliminate reasonable doubt. The study concludes that the English standard may be employed as a supplementary criterion for assessing the sufficiency of judicial certainty without replacing judicial knowledge. Such an application requires verification of the reliability of evidence, examination of reasonable alternative hypotheses, a reasoned response to existing doubts, and a clear explanation of the grounds upon which judicial knowledge has been formed. This comparative approach may enhance the transparency, predictability, and reviewability of criminal judgments.