Ken Livingstone has not disagreed with suggestions that his powers make London his "personal fiefdom" - saying it was the best way to bring about change.
Mr Livingstone denies corruption allegations
As a directly elected mayor he avoided "Sir Humphreys" delaying things like the congestion charge or more police.
Mr Livingstone, under fire over use of public funds, said if Londoners "don't like it they can get another mayor".
Boris Johnson, his Tory rival in May's London mayoral election, said Mr Livingstone was "drunk on power".
During his interview on BBC Radio 4's Today programme Mr Livingstone admitted his civil servants had taken part in political campaigns on his behalf but insisted they had done so in their own time.
And he insisted a campaign against the appointment of Trevor Phillips as head of the new Commission for Equality and Human Rights, run by civil servants in the mayor's office, was not motivated by his own personal dislike of Mr Phillips.
'Race relations duty'
Mr Livingstone launched the campaign in September 2006 after Mr Phillips made a series of speeches, as head of the now defunct Commission for Racial Equality, warning against increased racial segregation in the UK.
At the time the mayor accused Mr Phillips of "pandering to the right" and said he would "soon be joining the BNP".
Mr Livingstone defended his, and his staff's actions, saying "it is not a campaign against Trevor Phillips but what he was saying".
"I have a duty to promote good race relations and community relations in London and I took the view that the direction that Trevor Phillips was taking, at the CRE, was not just wrong but damaging and we launched a campaign to try and stop it.
"That is not anti-him. The fact that we don't like each other played no part at all."
Mr Livingstone defended London's mayoral system, which unlike traditional local authorities, allows the mayor to make many decisions without having to justify them to councillors.
The system also allowed the mayor to bypass the civil service, Mr Livingstone claimed.
"I do not work through endless layers of Sir Humphreys and Yes Ministers," he told Today, adding that "staff at City Hall work to deliver the agenda of the mayor".
When it was put to him that this sounded like a "personal fiefdom," he replied: "But that's exactly what Tony Blair - and I was opposed to the idea in the beginning set out to create - a directly elected executive.
"And if we didn't have that, I couldn't have got the congestion charge through a traditional council system, we couldn't have sustained the increase in the budget for policing."
He said the system "has allowed us to transform London - compare this with the glacial pace of change you get in national politics".
'Drunk on power'
He denied it lacked accountability, saying Londoners would judge him in May at the ballot box.
"If they don't like it, they can get another mayor and that is the best form of accountability."
Conservative candidate Boris Johnson, referring to claims in a TV documentary that Mr Livingstone drank alcohol during meetings, said: "Never mind the whisky, Ken Livingstone is clearly drunk on power.
"No matter how long someone has been in the job, they're not above accountability.
"More and more money is being raised by the Mayor; Londoners have a right to know where it is being spent and whether they are getting value for money."
Mr Livingstone also faces allegations of corruption at the London Development Agency, which has an annual budget of £450m.
It is claimed some of the organisations funded by the LDA subsequently went out of business without filing proper accounts.
The mayor's race adviser, Lee Jasper, was cleared by an internal review of any wrongdoing over alleged links to black organisations funded by the LDA.
But a cross party group of London MPs is calling for a full independent inquiry into claims that cash was given to groups which did little or nothing in return.
Mr Livingstone said the LDA tried to fund "marginal" groups that the market would not support and it was inevitable that some would fail.
"Many of those organisations we fund will fail and they will continue to do so.
"But the allegation that there is some network of corruption and money has gone to Lee Jasper's business associates - he has no financial interests in any of these organisations or any business link with any of the people involved in them."
Mr Jasper's deputy and business manager, Rosemary Emodi was forced to resign after she admitted lying about taking a free luxury trip to Nigeria.
Ms Emodi initially denied spending a weekend at a £200-a-night La Campagne Tropicana resort in Nigeria, last November, paid for by her hosts.
Mr Livingstone said Mr Jasper had not known about the holiday and had been "devastated" when the mayor told him about it.
Other candidates known to be standing in May's elections include former police chief Brian Paddick, for the Liberal Democrats, Sian Berry, for the Green Party, Gerard Batten MEP, for the UK Independence Party and Richard Barnbrook, for the BNP.