Sainsbury chief executive Sir Peter Davis will be a member of the nine-strong implementation group charged with delivering DEFRA's sustainable food and farming policy.
DEFRA is expected to report its strategy in early December and the group will be expected to ensure it is implemented.
The group will be chaired by Sir Don Curry, who chaired the Policy Commission on the Future of Farming and Food. Sir Peter, a commission member, will be the only retailer on the group. FDF director general Sylvia Jay is also a member.
Farming representatives will be NFU director general Richard MacDonald and Christine Tacon, general manager of Farmcare, the Co-operative Group's farm division.
The group held its first meeting this week, although Sir Don said he did not expect Defra's strategy to be ready until early December. It reports first to secretary of state Margaret Beckett and prime minister Tony Blair.
Last week a draft of Defra's policy was presented to a meeting of senior stakeholders chaired by food and farming minister Lord Whitty, but it received a critical response.
However, Sir Don said the response was not unexpected because it was a very early draft.
Speaking at a food and farming forum organised by the South of England Agricultural Society and sponsored by The Grocer, Sir Don emphasised: "The implementation group will deliver the strategy for the government. It will have responsibilities not just for Defra but across all government departments."
Curry also warned that the money put aside by the Treasury for the reconstruction of the farming sector was still dependent on further lobbying and the success of pilot schemes.