The changes, which will be backdated to April 2015, mean that a film costing £40m will receive an additional £1m towards productions costs.
Osborne said the changes reflect the global interest in the UK film industry, which has in recent years included the production of films such as The Theory of Everything, Gravity, and Avengers: Age of Ultron.
“A key part of our long term economic plan is supporting our creative industries that contribute billions to the economy and provide millions of jobs,” he said.
“We want to see more films made in Britain and that’s why we’ve made our film tax relief more generous.”
Amanda Nevill, chief executive at the British Film Institute, said: “The film tax relief is a key ingredient in the UK’s winning combination of outstanding filmmaking talent and crews, world-leading studios and facilities, and iconic locations.”