In his report on the future of the charity sector, the senior Labour MP said discussions would have to be held to decide if this would be a defined-contribution money-purchase scheme or a defined-benefit final-salary scheme.
This comes amid media reports Blunkett could be making a return to Government.
Rachel Maskell, Unite national office for the community and non-profit sector, welcomed the concept. She said: "This is a progressive template."
But she added: "There is the whole employee welfare agenda, such as stress and dignity at work, where trade unions historically have the expertise, and that needs to be firmed up to further improve working lives.
"We would also like to see a greater emphasis on stability when it comes to long-term contracts which would help secure funding, services for clients and the jobs of not-for-profit sector staff."
Give third-sector staff a portable pension, says Blunkett
David Blunkett has called for a portable third sector pension scheme for employees as they move jobs from charity to charity.
