Kerry, who is on a two-day visit to Pakistan for a strategic dialogue, dropped into the eatery early in the morning.
The 71-year American diplomat later tweeted his picture taken at the store in which he is shown dressed in a blue suit with his grey hair combed backwards.
"A little slice of home here in Islamabad at Dunkin' Donuts to start the day," Kerry tweeted. The picture was a hit on the micro blog.
Another tweet said, "Have been told that take a copy of this pic to your nearest Dunkin Donuts and they will pay your US visa."
More From This Section
His stop-over also raised eyebrows as he did not indulge in a traditional Pakistani breakfast but a popular American breakfast.
A tweet by Shaheryar Mirza said "John Kerry is at a Dunkin Donuts somewhere in Pakistan. Somewhere in Pakistan, PM Sharif is eating Halwa Poori alone."
Zaid Jilani said, "Actually culturally savvy on Kerry's part because many, many stateside dunkin donuts are owned or operated by desis.