The campaign, delivered by Ready10, features the England and Harlequins forward expaining why he is an ideal influencer to promote McDonald's fries.
Set in the surroundings of a rugby field and training gym, Marler shows off his bicep curl, breaks things and scowls to prove his 'hard man' cred, before revealing his softer side by using an unwitting dog as a prop.
He describes himself as "hard and crispy on the outside and soft and fluffy on the inside" – just like McDonald's fries.
The call to action is to "download the My McDonald's App now – or the dog gets it".
McDonald's is offering customers 24 deals over 23 days to brighten up the month of January.
The collaboration is the latest in a series of creative campaigns to promote the My McDonald's App. Other celebrity partnerships have included Love Island stars Alex Bowen and Olivia Bowen Buckland, YouTube football sensation Emmanuel "Manny" John Brown, and grime artist Lethal Bizzle.
Greg Double, associate creative director at Ready10, said: "It is a nice feather in the hat for the PR industry as a whole. This was 100 per cent scripted at Ready10 HQ, shot with a single-shooter and is now getting the most ridiculous 'real people' reaction online. You cannot tell me a big ad agency could have done any better – PR can play in this space.
"I am convinced that this style of 'self-aware' content is a trend more brands (and clients) should consider. People are not mugs. They know they are being marketed to by brands, so it's often a great device just to tell them straight and make it funny."