Before the pandemic, Jo Rawlinson would buy four-year-old Mason Wanstall one of the fast food meals when he came to stay over at her house.
But the virus crisis has left him feeling upset as he is unable to see her.
Ms Rawlinson says Mason, who will be unable to have a birthday party when he turns five on April 4, is struggling to understand what is happening due to his autism.
The gran-of-three told KentOnline: "My grandson is nonverbal autistic - he is just starting to talk bless him.
"He is a really happy and loving chap who really does look forward to coming round my house for the night and having a McDonald's.
"Autistic children really like their routine so as he can’t come round to nanny’s house, I wanted to try and make sure he had something to look forward to."
She asked staff at the Chestfield McDonald's branch, near Whitstable, if they could help.
The 49-year-old added: "McDonald's were brilliant - they gave me boxes, cups and all sorts to make up his normal Happy Meal.
"Although it won’t be with me, it will be with mum and dad, it will makes things better for him.
"Thank you to McDonald's for helping my grandson and enabling him to have his special treat."