Speaking in a Christmas lecture at the Royal Television Society, Dyke criticised the Trust for being "unduly slow and bureaucratic, expensive to run and [responsible for having] created inbuilt conflict".
Dyke's comments echo those of culture secretary Ben Bradshaw and shadow culture secretary Jeremy Hunt, who have both recently claimed that the Trust is simply not working as a regulator for the BBC.
In the speech, Dyke - who was BBC director general from 2000 to 2004 - said that "conflict" generated by the Trust has left the BBC "without a supportive board or chairman and the director general without the cover any chief executive needs".
He added: "In any organisation the chairman-chief executive relationship is all important and here the structure works against it being effective.
"Most of all, when the organisation is under attack, as it currently is, the chairman isn't free to defend it as he should because he's really the regulator."
Despite the criticism, Dyke stressed that he was not directly attacking Trust chairman Sir Michael Lyons, who has done a good job "in what is an impossible structure".
Instead, Dyke believes that Ofcom is the most logical choice as regulator for BBC activity. He also called for a more effective board structure to be implemented at the corporation and for executive salaries to be reduced to protect its "long-term interests".
In response, a Trust spokesman said that the organisation was just "getting on with the job of making sure that the BBC delivers for licence-fee payers". He added that Dyke is "entitled to his opinion".
Dyke, who is currently chairing a creative industries review for the Conservative Party, recommended last month that the licence fee should be ditched to save over £100m a year in administration costs.