Playing down concerns about the city’s transport network, he also insisted the Games would make money.
“We are going to be selling London,” he told the BBC, adding that the Games had already brought “fantastic investment”.
Meanwhile, Culture Secretary Jeremy Hunt has called a planned strike by UK border staff on the eve of the Games “an absolute disgrace”.
It comes after International Olympics Committee president Jacques Rogge told reporters he was satisfied with security arrangements for London 2012.
Mr Johnson told BBC One’s Andrew Marr Show: “If you look at what Jacques Rogge had to say last night, he’s been in London for a few days, he thinks that our city is as well-prepared as any city in the history of the Games.”
The mayor said: “So far the traffic system and the transport networks generally are holding up well, touch wood.”
He added: “I think possibly what we are going through at the moment as a nation, as a city, is that necessary pre-curtain up moment of psychological self-depression before the excitement begins on Friday.”
Montreal hosted the Olympics in 1976 and took 30 years to pay off the Games’ bills, while the cost of staging the 2004 Olympiad is believed to have contributed to Greece’s financial crisis.
But Mr Johnson said: “The heads of most of the world’s great businesses are coming to London in the course of the next few weeks and we are going to be showing what London has to offer, making it clear there are fantastic opportunities for investment…. We are going to be selling London.”
He said: “The Olympic Games have already been responsible for fantastic investment in this city. Pension funds from across the world are investing in the Olympic sites right now… to say nothing of all the transport investment, which is transforming London.
“I defy the critics of the Olympics to say that this is not producing economic benefits for the city.”
He said 512,000 people were understood to have turned out to see the torch relay on Saturday and that most people in London were looking forward to the opening ceremony.
Jacques Rogge said the IOC was satisfied with security arrangements for the Games
Meanwhile Mr Hunt lambasted members of the PCS union who have voted to go on strike on Thursday, the eve of the opening ceremony.
The action will involve staff across the Home Office, including the UK Border Agency, the Identity and Passport Service and Criminal Records Bureau.
Mr Hunt told BBC Radio Five Live’s Sportsweek programme: “They are totally out of tune with the mood of the country.”
He said: “I find it extraordinary. I mean we’ve got 600-odd staff who man the immigration terminals at Heathrow, and you’ve got 60,000 to 70,000 volunteers who are giving their time over the next six weeks, completely free of charge, and you know – they may or may not have a legitimate industrial grievance, but this is surely not the time to pursue it.”
Mr Hunt added: “It’s an absolute disgrace. It’s totally out of sync with the way everybody else is behaving. If, you know, Labour and the Conservatives and the Liberal Democrats can come together to unite behind the Olympics I think this is just a moment when you’ve just got to read the mood of the country a bit better.”
He denied the strike would impact on preparations for the Games, adding: “We have a contingency plan in place and I am absolutely confident that we will get everyone into the country.”
Asked by presenter Gary Richardson about the possibility of sacking the strikers, he replied: “I can tell you amongst ministers there have been people asking whether we should be doing that but I don’t want to escalate things by talking about that right now because I know amongst those 600 people there are lots of people who want to do the right thing and turn up for work.”
BBC © 2012