The Labour leader said the move would bring together England, Scotland, Wales and Northern Ireland, while giving workers a well-deserved break.
Under the plan, it would mean there would be public holidays on St David's Day (March 1), St Patrick's Day (March 17), St George's Day (April 23) and St Andrew's Day (November 30).
"The four nations that make up our great country have rarely been more divided due to the damaging and divisive policies of this Conservative Government," Mr Corbyn said.
"But where Theresa May divides, Labour will unite our four nations. A Labour government will make St George's Day - England's national day and Shakespeare's birthday - a public holiday, along with St David's Day, St Andrew's Day and St Patrick's Day.
"And we will ask for the support of the governments of Wales, Scotland and Northern Ireland so that the same four holidays can be enjoyed across the United Kingdom.
"These holidays will be a chance for workers to spend time with their families, in their communities and with their friends. But they will also be a chance to celebrate the national cultures of our proud nations."