The move aims to get multinationals — particularly tech giants — to pay more into government coffers hit hard by the pandemic.
"I am delighted to announce that today after years of discussion G7 finance ministers have reached a historic agreement to reform the global tax system," said British Finance Minister Rishi Sunak, who was chairing the talks in London. "It's complicated and this is a first step," Sunak said.
German Finance Minister Olaf Scholz described the deal as "historic."
"It is very good news for tax justice and solidarity and bad news for tax havens around the world," Scholz said in a statement, adding: "Companies will no longer be in a position to dodge their tax obligations by booking their profits in the lowest-tax countries."
French Finance Minister Bruno Le Maire said the group's commitment was a "starting point," pledging to hike it further.
"This is a starting point and in the coming months we will fight to ensure that this minimum corporate tax rate is as high as possible," Le Maire said.
US Treasury Secretary Janet Yellen said the move would "help the global economy thrive, by leveling the playing field for businesses and encouraging countries to compete on positive bases."