The Beaverton, Oregon-based company said that initially five products from its Alpha Project line will be available from the nike.com site.
After a three-month trial, the company plans to relaunch the program with a wider variety of products.
Nike hadn't planned to delve into e-commerce quite this soon, but mounting speculation about its plans spurred the company to go online sooner. "We took a look at the landscape out there and completed some due diligence," said Nike spokesman Vada Manager.
Some retailers are uncertain about how the Nike.com sales will affect their business, said Manager. "But the larger retailers see it as inevitable."
The Web site, which already gets about 1 million hits a month without any transaction capability, will include a "store locator" feature. So far, the company is not planning to advertise the site, but that could change when the company begins selling all of its products on the Internet, now scheduled for sometime in the summer.
Reuters contributed to this report