Awarded only to members of the United States Merchant Marine, the Mariner's Medal recognizes seamen who were killed or wounded as a direct result of conflict against an opposing armed force; in specific, it was awarded to any seaman who while serving in a ship during a war period is wounded, suffers physical injury, or suffers through dangerous exposure as a result of an act of enemy of the United States.

In the event any such seaman dies from the wounds or injuries before the award can be made to him, the medal may be presented to the person named in the War Risk Policy as his beneficiary.

Although the Merchant Marine Mariner's Medal is considered a federal service decoration, it may be worn on the uniforms of active duty service members.

Designed by Paul Manship, subsequent awards of the medal are represented by 5/16th inch gold stars affixed to both the suspension ribbon and the ribbon bar.

Also on originals, the designer's initials "P.M." (Paul Manship) are below the wreath, to either side of the cuff; subsequent re-issues of the medal lack these devices.