The BHA said the commission had allowed the charity, after a long campaign, to amend its charitable objects to include the advancement of humanism.
One of the objects is now "the advancement of humanism, namely a non-religious ethical life stance, the essential elements of which are a commitment to human wellbeing and a reliance on reason, experience and a naturalistic view of the world".
The Charities Act 2006 specifically recognises that the promotion of religion is a charitable purpose. During the passing of the act, humanist groups argued that the promotion of non-religious beliefs should be given the same treatment as religious beliefs under law. However, attempts to amend the law were unsuccessful.
Andrew Copson, chief executive of the BHA, said the commission’s decision was another step towards breaking down "an anachronistic distinction in the law".
"The BHA is delighted with its new objects, which represent a considerable legal advance for fair treatment of religious and non-religious organisations," he said.
Negotiations with the commission had taken more than a year, but the commission had been "very supportive of our views" and helpful throughout, he added.
A spokeswoman for the commission said: "Both religious organisations and non-religious organisations promoting the moral and spiritual improvement of the community may have purposes that are potentially recognisable as charitable.
"The requirement of public benefit for both kinds of purpose is considered by the commission to be the same."