Getting the most out of a minimal budget and shooting schedule, it was so well directed by Robert Florey that the New York Times' critic Frank Nugent treated it like an A-release, declaring:

“Surprise, surprise! King Of Alcatraz is not about Alcatraz at all, but about a fugitive public enemy and his mob who commit piracy on the high seas.... It's a trim little melodrama, tightly written and logically contrived, and Paramount's Robert Florey deserves a round of applause for keeping it spinning so furiously....

“Maybe our memory is failing, but our impression is that it actually contains a couple of plot turns new to the screen. One is the notion of a lamming gangster and ten of his picked men making a getaway as the only passengers aboard a vagabond-cruise freighter. Another is the employment of ship-to-ship wireless to permit a nurse on the vessel to perform a critical operation under the dot-dashed guidance of a surgeon on the other. And finally there is the incredible novelty of seeing both the hero and his pal rendered hors de combat in the crucial struggle, with rescue coming from a most unexpected quarter....”