Foreign ministers from the four nations met at the UN headquarters to step up their campaign even though there is no broad acceptance within the 192 UN members on how to reform the world body's supreme peace and security body.
Germany's Foreign Minister Guido Westerwelle stressed that the campaign for change has majority backing within the United Nations.
"It is not a minority idea, it is something that a clear majority wants: reform of the United Nations," he said.
"We think it is certainly not in our national interest what we are doing here. If the United Nations will not reflect the world as it is in our days, the authority of the United Nations will decrease," he warned.
"Pressure is mounting here at the United Nations for the UN membership to finally face the challenge of addressing Security Council reform in a realistic manner, adjusting it to the current geo-political realities," said Brazil's Foreign Minister Antonio de Aguiar Patriota after the meeting.
The four nations believe "that we should work towards concrete outcome in the current session of the general assembly," which ends in September, he added.
India's Foreign Minister S.M. Krishna said "the response that we are getting is overwhelming and we feel confident that we can move in that direction."
He said the four would "press ahead for reform of the Security Council on an urgent basis."
Britain, China, France, Russia and United States have been the only permanent members of the Security Council, able to veto any resolution, since its creation in 1945. The number of non-permanent members was increased from six to 10 in 1963.
Brazil, Germany, India and Japan, the so-called Group of Four (G4), renewed their longstanding campaign to get permanent seats on the Security Council last year.
On top of the G4, African nations believe they should have up to two permanent seats on the council, with South Africa, Nigeria and Egypt all considered contenders. Arab and Latin American nations are also demanding stronger representation.
Change requires a two thirds majority vote at the General Assembly, however, and reform efforts have repeatedly floundered on which nations should get a permanent seat and how other places should be divided up.
The United States and other permanent members oppose various parts of the G4 ideas made public so far. Diplomats say China could try to block India or Japan getting a permanent place.
Patriota acknowledged that there is still "no consensus on the important aspects of the reform" and the four are "testing different ideas."
"The objectives are well known, I think the challenge is to find a formula that will obtain the widest possible acceptance."
Japan's State Secretary for Foreign Affairs Takeaki Matsumoto put his country's backing behind the new commitment "to gain a concrete outcome."