HIV screening will be offered by Marie Stopes International at its nine centres in Britain.
All men and women attending the clinics will be able to take the tests, with the measures designed to cut down on the estimated 25% of HIV-infected people living in the UK with no knowledge that they have the condition.
People taking the test could ensure that they get an early diagnosis and still live a long, healthy life.
Some expectant mothers using unplanned pregnancy services could be entitled to have the test for free on the NHS after several care trusts agreed to foot the bill in certain circumstances.
The Marie Stopes initiative has come into effect following the trusts' change in policy, so some women could be able to get the screening for free now.
Marie Stopes is currently offering the HIV screening at its clinics in Maidstone, Manchester, Leeds, London, Reading, South London and West London, with its Bristol and Essex centres set to offer the service soon.
Tracey McNeill, vice-President of UK and Western Europe at Marie Stopes International, said: "We are pleased to now offer HIV testing and we hope that the more than 70,000 men and women who visit our clinics annually will take up the opportunity to check their HIV status."