The agreement marks a huge turnaround for both the not-for-profit One Laptop per Child (OLPC) foundation and Intel.
In May this year, Nicholas Negroponte, the founder of OLPC, said the silicon giant "should be ashamed of itself" for efforts to undermine his initiative.
He accused Intel of selling its own cut-price laptop - the Classmate PC - below cost to drive him out of markets in the developing world.
"What happened in the past has happened," Will Swope of Intel told the BBC News website. "But going forward, this allows the two organisations to go do a better job and have a better impact for what we are both very eager to do, which is help kids around the world."
Nicholas Negroponte, founder of One Laptop per Child, said: "Intel joins the OLPC board as a world leader in technology, helping reach the world's children. Collaboration with Intel means that the maximum number of laptops will reach children."
Intel inside
The new agreement means that Intel will sit alongside the 11 companies, including Google and Red Hat, which are partners in the OLPC scheme.
It will also join rival chip-maker AMD, which supplies the processor at the heart of the $100 laptop.
"Intel's apparent change of heart is welcome, and we're sure they can make a positive contribution to this very worthy project for the benefit of children all over the world," read a statement from AMD.
Initially there are no plans to switch the processor to one designed by Intel. However, the servers used to back-up the XO laptops, as they are known, will have Intel technology at their core.
Decisions about the hardware inside the XO laptop would be made by OLPC, said Mr Swope.
"OLPC will decide about which products they choose to offer or not offer," he said.
OLPC, however, indicated that it would consider using Intel chips in its machines in the future.
Walter Bender, head of software development at OLPC, told the BBC News website that he believed OLPC would eventually offer different computers with different hardware.
"I think we will end up with a family of products that run across a wide variety of needs," he said. "Intel will be part of that mix."
Price test
In addition, the partnership will have a practical pay off for software developers.
"Any software you build is going to run at least on our two platforms," said Mr Swope.
An application developed for the XO laptop should work on the Classmate and vice versa.
"That's the exciting thing for me," said Mr Bender.
Currently both laptops are being tested in schools around the world. In parallel, OLPC is finalising orders for the first batch of computers.
Participating countries are able to purchase the XO in lots of 250,000. They will initially cost $176 (£90) but the eventual aim is to sell the machine to governments of developing countries for $100 (£50).
Intel says it already has orders for "thousands" of Classmates, which currently cost over $200 (£100).
Like the OLPC machine, Intel expects the price to eventually fall.