Prosecutors are said to be ministers of justice and protectors of the public interest. Drawing on procedural justice and the re-conceptualization of legitimacy, this study argues that for prosecutors to be seen to act in the public interest, they should be perceived to exercise their powers legitimately, and, more specifically, for the public to feel that prosecutors make decisions that are morally aligned with their own. Using a random survey of the Hong Kong general population, it is found that when prosecutors are perceived to act in procedurally just ways, the legitimacy of the justice system, as well as the moral alignment with prosecutors and the courts, are enhanced in the minds of the public. Legitimacy and moral alignment are also associated with cooperation with the legal authorities and compliance with the law.