Students taking online courses from prestigious US universities will be able to take final exams in a global network of invigilated test centres.
Online universities have been claimed as a "revolution" for higher education and this will be seen as a significant step forward.
Education company Pearson will provide test centres for the edX online courses provided by Harvard and MIT.
This will give online courses "real world" value, says the edX president.
As well as providing supervised exam centres they will also authenticate the identity of online learners.
It will also see formidable partnership between some of the world's most famous universities and the world's biggest education firm, Pearson.
This year has seen growing interest in the idea of delivering university courses online - allowing universities to reach much bigger numbers of students and cutting the cost of tuition.
There have been claims that the emergence of online universities, and the accessibility of lectures and study groups online, will have a far-reaching impact on the traditional model of higher education.
Alliances of major US universities have been in a race to develop online courses - in a kind of academic format war - with the edX project providing courses from Harvard, the Massachusetts Institute of Technology and the University of California, Berkeley.
A rival project called Coursera was launched by academics from Stanford in California and is now offering courses from 16 universities, including the University of Edinburgh.
So far all the courses, delivered entirely over the internet, are available free - and almost all of them are not formally accredited by the university.
In a matter of months, these courses have acquired hundreds of thousands of students. In the UK, about 40,000 students have signed up for courses on the Coursera platform.
MIT said that a pilot course, run earlier this year, had been studied by more students than all the university's previous living alumni combined.
But a practical question for these online students has been how their work can be recognised - and how such courses can overcome the risk of cheating and how they can validate the identity of the candidate.
The deal announced on Thursday will allow students who have studied online to sit edX exams in supervised centres, where their work can be formally tested.
Students, who will have to pay a fee for this service, will be able to use test centres run by Pearson VUE, which has 450 centres in 110 countries.
The intention is that students will be able to show employers that they have taken these courses, which have been set by some of the biggest names in higher education.
However, with many students at these universities paying more than $50,000 per year for their full campus experience, there will still be a distinction between degrees from the universities and these online versions.
"Our online learners who want the flexibility to provide potential employers with an independently validated certificate may now choose to take the course exam at a proctored [supervised] test site," said Prof Agarwal, who had been director of MIT's Computer Science and Artificial Intelligence Laboratory before becoming the inaugural president of edX.