The scientists said the improvements were likely to be largely due to the transition to less toxic medicine combinations, with more drug options for people infected with drug-resistant HIV strains, and better adherence to treatment. Those aged 20 who started antiretroviral therapy in 2010 are projected to live 10 years longer than those first using it in 1996, it found.
The World Health Organization now recommends ART should be given as soon as possible after diagnosis to everyone with HIV.
The study, published April 10 in The Lancet journal, found that 20-year-olds who started taking antiretroviral treatment in 2010 are predicted to live around ten years longer than those who first started similar treatment in 1996 when HIV drugs became widely available.
Between 1996 and 2013, the life expectancy of 20-year-olds treated for HIV increased by nine years for women and 10 years for men.
Life expectancy in the United States is 78.9 in the U.S. and 80.1 in the UK.
During this time, measures of HIV improved - with the average immune cell count after a year of treatment increasing from 370 cells per microlitre of blood in 1996-1999, to 430 cells per microlitre in 2008-2010, while the proportion of people with a low HIV viral load increased from 71% to 93%.
Adam Trickey, lead author of the study, said: "Newer drugs have fewer side effects, involve taking fewer pills, better prevent replication of the virus and are more hard for the virus to become resistant to".
However, Trickey said further efforts are needed if life expectancy is to match that of the general population.
Authors of the study hope that the findings will "decrease stigmatisation of people living with HIV and help them to obtain insurance and employment".
The study authors looked at 88,500 HIV positive people from Europe and North America who were involved in a total of 18 studies.
Data says that life hope in the overall population without people infected with the AIDS-causing virus is 79 years for male and 85 for females in France and in the case of the US it is 78 for male and 82 for female.
The paper said a European 20-year-old with HIV could now expect to live to almost 70 years old.
He added: "Since modern treatment is highly effective with low toxicity, deaths in people living with HIV are unlikely to be reduced by further development of drugs".
"It's a tremendous medical achievement that an infection that once had such a awful prognosis is now so manageable, and that patients with HIV are living significantly longer", Helen Stokes-Lampard, chairperson of the Royal College of General Practitioners, told BBC News.
Standard antiretroviral therapy (ART) consists of the combination of antiretroviral (ARV) drugs to maximally suppress the HIV virus and stop the progression of HIV disease.
Both Dr Brady and Professor Stokes-Lampard pointed out that one in seven people with HIV are unaware they have the virus and emphasised the importance of increased testing.
"Overall, the results of the study are very good news", Whitworth told CNN. "Those are the places doing the least well".