The money, equivalent to 1.1 million euros or 1.5 million dollars, is to bolster the host's Condom supplies, a move health officials predict will be necessary amid the tournament's "spirit of festivity."
Britain said the aid, announced shortly after a visit to London by South African President Jacob Zuma, would help the country's aim to buy one billion condoms at a time the AIDS fight has been hit by the economic downturn.
"As a consequence we face the very real prospect that progress on tackling HIV will go into reverse," said international development minister Gareth Thomas.
"That is why (Britain) is supporting South Africa's leadership and drive to turn the tide on their epidemic."
A top medical officer unveiled plans last month to increase Condom supplies ahead of the football tournament, due to start in less than 100 days.
"There's going to be a large number of people who will be descending onto the country," said Victor Ramathesele, general medical officer for South Africa's 2010 organising committee.
"There's going to be a spirit of festivity and... there could be a more than usual demand for measures such as condoms," he said.
Zuma left Britain Friday after a three-day state visit, which was marred by a row over British media coverage of his polygamy and a failure to agree on Zimbabwe.
His administration has stepped up the battle against AIDS, and South Africa now boasts the world's largest anti-retroviral programme after years of government failure to roll out the life-saving drugs.
South Africa hosts the continent's first World Cup in June and July.