The University of Texas (UT) System is joining the edX online platform project set up by Harvard and the Massachusetts Institute of Technology (MIT).
The University of Texas says it could offer degree credits through the online platform, with a tuition fee attached.
Chancellor Francisco Cigarroa said he wanted Texas to "lead this revolution".
"The UT System does plan to eventually offer courses for credit. There will be a tuition charge for credit-earning courses, but the amount hasn't been determined," said Jenny LaCoste-Caputo, spokeswoman for the UT System.
This would be a major step for this new wave of online universities set up this year by top universities in the US.
The edX alliance, launched this year, already includes MIT, Harvard and the University of California, Berkeley. But so far these have offered free courses which do not carry credit towards degrees.
The latest recruit to edX - with more expected this autumn - is one the biggest public university systems in the US.
The network of universities in the University of Texas System has more than 200,000 students, 19,000 academic staff and an annual operating budget of $13bn (Â£8bn).
There has been something of an academic format war emerging with a rival Coursera platform, started by academics from Stanford in California.
Coursera now has 1.6 million students around the world studying courses from more than 30 leading universities, including Edinburgh and the University of London.
The University of London reported that 9,000 students had signed up within the first 24 hours.
There have been online courses in the US and UK for a number of years - but there has been a recent surge of interest as self-study courses have been put online by some of the world's most famous institutions.
These can be studied anywhere in the world and the assessment is also carried out online.
Helping to drive the expansion of online courses in the US has been a concern about the high costs of university and the rising level of student loan debts.
Gene Powell, chairman of the UT System Board of Regents, said the partnership with edX is intended to help them reach a "wide range of students, raise graduation rates and cut the cost of higher education".
The latest expansion in prestigious online universities in the US includes plans to charge for courses which will count towards degrees.