The anniversary comes amid renewed tensions between the two countries. The UK has owned the Falklands since 1833, but Argentina, who call them the Malvinas, still claim the islands as their own.
Services today will remember those who died in the conflict: 255 British soldiers and 650 Argentines.
In a statement, David Cameron said he remains committed to British sovereignty of the islands, saying in a statement: "Britain remains staunchly committed to upholding the right of the Falkland Islanders, and of the Falkland Islanders alone, to determine their own future. That was the fundamental principle that was at stake 30 years ago: and that is the principle which we solemnly reaffirm today.
"We are rightly proud of the role Britain played in righting a profound wrong. And the people of the Falkland Islands can be justly proud of the prosperous and secure future they have built for their islands since 1982.”
In Argentina meanwhile, President Cristina Fernandez de Kirchner is expected to visit the port of Ushuaia to commemorate the dead, before leading a rallies across Argentina and lighting an “eternal flame” as a mark of respect.
Margaret Thatcher was Prime Minister at the time of the war, but she is not expected to take part in the commemoration because of ill health.
The latest row over the islands that frames today’s events erupted after Argentina asked Britain for negotiations over the islands. Britain refused, with Argentina complaining to the UN of the UK’s “militarisation” of the south Atlantic, after a new warship was sent to the area and Prince William was stationed on the islands as a search and rescue pilot.