He hit back at a feeling that everybody in authority was suspect and that people making national and international decisions were "assumed to be doing so for some devious reason".
The Home Secretary and Brightside MP spoke out amid controversy about the Government's case for war on Iraq and about the death of weapons expert Dr David Kelly.
Rows have been fuelled by fierce clashes between the Government and the BBC and accusations about the role of spin in Downing Street.
Today Mr Blunkett said: "If there is to be one lasting challenge for politicians and journalists when the events of recent months have played out, it will be to persuade the public that either of us is worth trusting."
He used an article in The Times to underline a need to "reflect upon" trust in politicians, the media, institutions and "in ourselves and our capacity as a society" to do what is right. It was "deeply damaging" that many people had switched off from politics, said Mr Blunkett.
He argued trust was an issue "for both politicians and the purveyors of information".
Mr Blunkett also renewed a call for people and communities to take responsibility for their lives and to be given the ability to act to shape society as active citizens.
He added: "Sometimes, those in positions of leadership and responsibility have to take decisions even in the face of considerable controversy and genuine division.
"This is also part of the living democracy that cannot happen if gossip, tittle-tattle or the embellishing of opinion is elevated to a point where genuine differences are subsumed in personalised acrimony."
Mr Blunkett added: "I am not in politics to moan from the sidelines but, with my colleagues, to present an analysis and to put forward solutions.
"Then it is for the people to make their judgement."