The British star spoke to dozens of lawmakers and campaigners in the grand Speaker's House of Parliament on Wednesday.
Sir Elton set up his AIDS Foundation in 1992 and has helped raise millions of dollars to prevent HIV infections and reduce stigma.
"This evening I was privileged to welcome Sir Elton John and acknowledge his exceptional contribution to the global fight against HIV and AIDS — personally and through the Elton John AIDS Foundation," Commons Speaker Lindsay Hoyle said on X.
"His work embodies the solidarity and kindness that defines our shared humanity," he added.
In the UK, the charity recently led campaigns to extend a pilot government program to test people visiting hospitals' emergency rooms for HIV.
Under the program, which was recently introduced in London and other cities with a high prevalence of HIV cases, anyone 16 or older who has their blood tested in an emergency room will also get tested for HIV, Hepatitis B and Hepatitis C, unless they opt out of the testing.
Sir Elton's charity has urged the government to expand the service, which officials say has been key in discovering hundreds of undetected cases of HIV.
"Routine HIV testing in emergency departments is especially good at finding people who would otherwise not receive a test, most often from marginalised communities who are being left behind in our progress on HIV," said Deborah Gold, chief executive of National Aids Trust.
On Wednesday health officials confirmed that the program will be scaled up to 46 more emergency departments, helping reach the estimated 4500 people in England who could be living with undiagnosed HIV.
The parliament reception for Sir Elton came ahead of World AIDS Day, which takes place on Friday. The UK hopes to achieve zero HIV transmissions in England by 2030, in line with World Health Organisation goals.
Earlier on Wednesday, Prime Minister Rishi Sunak also paid tribute to Sir Elton's AIDS Foundation, saying he was pleased its work was being celebrated in Parliament.
"Sir Elton has been a powerful voice for change in the UK and the world," Sunak told lawmakers.
"Through the brilliant work of the AIDS Foundation he has raised awareness of the issue, reduced stigma and saved lives."
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