The vegetarian singer is furious the fast food giant are displaying his picture - along with his former Beatles band mates Ringo Starr and the late John Lennon and George Harrison - at one of their outlets in his home city of Liverpool to attract more customers.
The musician's spokesperson said: "What sort of morons do McDonald's think Beatles fans are?"
"It's ridiculous and insulting to use images to peddle hamburgers. Fans should boycott McDonald's - and not just in Liverpool."
Paul is president of the Vegetarian Society of Great Britain and an ambassador for People for the Ethical Treatment of Animals (PETA) A PETA spokeswoman said: "He became a vegetarian after watching lambs play in a field outside his home and surely would not want anyone to use his likeness to help promote meat."
"We hope anyone who sees his picture on the wall will be reminded that he's a vegetarian and skip the Big Mac for a veggie burger."
A McDonald's spokesperson denied using The Beatles' images to boost sales, insisting they wanted to "acknowledge the outstanding contribution The Beatles made to both local and global culture."
It was reported earlier this week that Paul - a vegetarian since 1975 - has been influencing new love Nancy Shevell's attitude towards food.
A source said: "Nancy has toned down her super-Republican views and given up her beloved steaks, which shocked us."
"When they traveled around America this summer, they lived on avocado sandwiches and tomato soup. Now Nancy orders veggie food all the time."
