Wei said that the policies now in place will "serve as the foundation for the big society for years to come" and he now believes there is work to be done outside government to help build a big society locally.
He will take up an as yet unspecified role at the Community Foundation Network, a national body linking and supporting community foundations across the UK.
Prime Minister David Cameron said: "Nat has worked incredibly hard over two years to help develop policies that support the big society. He has played an important role in delivering key initiatives like Community Organisers, National Citizen Service, and the Big Society Bank. I wish him every success in his new role with the Community Foundation Network."
Wei, a member of Teach First’s founding staff team, was made a government adviser before the election and appointed as a Lord in May last year.
But in February, Wei said he was forced to cut back the number of days he acted as an unpaid government adviser from three days a week to just two after admitting the role had left him struggling financially.
The government’s big society agenda has also come under repeated attack over the past year, which has led the Prime Minister to defend the policy on more than one occasion.
Wei said: "I look forward to taking on this new role where I will be getting out into communities and advising investors, organisations and community leaders in helping them to transfer power and resources from the centre to where it is really needed."
He added: "It has become clear to me in the past few months that there is much work to do outside of government to advise people, communities, and what I call civic entrepreneurs to help build the big society locally and make it easier for everyone to get involved."
The Cabinet Office has confirmed he will continue in his role in the House of Lords.
