The BBC is to close some websites and invest in those that add "sufficient public value", in response to the Graf report's recommendations.
Michael Grade spoke at the CBI conference on Monday
The report - commissioned by the government to examine the BBC's online services - was published in July.
The BBC board of governors announced on Monday a series of measures to achieve a "distinctive online operation".
BBC chairman Michael Grade said the changes to bbc.co.uk showed the BBC was going through a "radical change".
Ashley Highfield, director of the BBC's new media and technology, said the recommendations marked a "new era" for bbc.co.uk.
"To maximise public value, and reach as many people as possible by providing audio/video rich, distinctive, innovative content we will decommission or close those sites that do not add sufficient public value and reprioritise this investment into services that do," he said.
"We are committed to building on the work we've already begun to provide a simpler, more open framework for engaging more collaboratively with the industry," he added.
And Mr Grade, speaking at the CBI conference in Birmingham, highlighted the governors' tighter remit for the BBC's online services.
He said the new remit focuses on how "bbc.co.uk can be made more distinctive, and deliver more public value" in the online market.
The remit includes plans for:
At least 25% of the BBC's online content to be supplied externally by 2006
Deliver greater public value through the online medium
Link bbc.co.uk to more external, high-quality third-party content.
Ensure bbc.co.uk makes a substantial contribution to towards a 100% digital UK
Make bbc.co.uk easier for users to find their way around and to give feedback to the BBC
Make the BBC's archives easier to access
Commit to commissioning a major independent review of bbc.co.uk in three years' time
Immediately after the Graf report was published, it was announced that five BBC websites were to close as they were not considered distinctive enough from commercial alternatives.
They included the What's On listings site, Fantasy Football, the Games and Surfing portals and the Pure Soap site.
The new closures - to be announced before Christmas - will take the total cuts to bbc.co.uk to around 10% of the online content budget.
Philip Graf made a number of recommendations
Cutbacks have also been made to BBC investment in lifestyle areas including music, gardening, antiques and motoring. There will also be changes to the local Where I Live sites.
In addition, some sites have been told to strive to become more distinctive as a result of the report.
The Film site, for example, is now focused on educating people about the creative process of film-making and allows audiences to share their own films.
The BBC news website - and other news-related content - will be exempt from plans to supply 25% of online content from external sources.
After publication of the report, which was complied by former newspaper executive Philip Graf, the government told the board they had four months to redraft their remit for bbc.co.uk.
During his speech at the CBI conference, Mr Grade said: "We are publishing new, much more tightly drawn objectives. They focus on how bbc.co.uk can be made more distinctive, and deliver more public value, in this developing and growing market.
"We've reviewed our portfolio of websites and closed down some sites because they would not meet our new test of public value.
"There are further closures and spending reallocations within online to come as we specify what we won't do, as well as what we will."
Mr Grade added that planned changes to the governance system were "too pressing" to wait until the outcome of the Charter review debate.
As a result, the board will now be supported by a dedicated Governance Unit and the governors themselves will move away from management.
He said the governors would be moving to new premises away from the BBC's main Broadcasting House and White City sites.