Company bosses say they want to apply the same standards to all their routes including the Cairnryan to Belfast crossing.
This rule comes into force on the same day everyone will be required to wear coverings on all public transport in England.
The company has asked for everyone using terminals, bus transfers or passenger walkways, as well as onboard to wear a face masks or a face coverings.
Exceptions will be made for children under three and anyone with an illness or disability that prevents them from wearing one.
A spokesperson from Stena Line said: "Based on government advice, we have added this requirement to our already extensive COVID-19 safety measures which are intended to safeguard both the health of our passengers and crew and to ensure maximum safety whilst travelling by ferry."
More information can be found on the Stena Line website.