Tessa Jowell will be Labour's spokeswoman on third sector issues until a new party leader is appointed.
Former ministers are retaining their positions in the shadow team until a successor to Gordon Brown is in place. But Angela Smith's defeat in South Basildon and East Thurrock created a void, which will be filled by Jowell, shadow Minister for the Cabinet Office.
Jowell said it would be up to the new party leader to decide whether Smith's successor would use the title shadow Minister for Civil Society or retain the third sector title.
She told Third Sector that Labour multiplied the government's engagement with the voluntary sector and invested heavily in it, and contrasted this to the coalition government's "utterly woolly" big society idea.
"People I represent in the poorest part of my constituency think it has absolutely nothing to do with them," said the MP for Dulwich and West Norwood.
She said her party would scrutinise whether Nick Hurd's appointment as a parliamentary under-secretary of state, rather than a minister of state, amounted to a downgrading of the role, but that she was not getting hung up on titles.
"Nick Hurd's appointment came as no surprise," said Jowell. "He will be judged on what he achieves for the third sector."