The Hammers will leave their Boleyn Ground home of 112 years at the end of the current season and begin their new existence as anchor tenants of the 54,000 seater stadium, at a reported annual cost of £2.5m, from the start of the 2016/17 campaign.
The Information Commissioner has ruled that the terms of the deal must be made public, after Freedom of Information was requested by campaigners - many fans of rival football teams up and down the country.
But the London Legacy Development Corporation (LLDC) and the Hammers have attempted to block any release of information, insisting that details of the deal involving the largely taxpayer-funded stadium must remain private for commercial confidentiality and Johnson has revealed the east Londoners are even considering legal action, as reported by Sky Sports.
'Show some pride and stop being miserable'
But during Mayor's questions at London's City Hall on Wednesday, Johnson defended the decision to hand the Hammers the keys to the iconic stadium, saying they will provide a genuine legacy unlike other Olympic Stadia in other countries.
"The jist of the matter is that this has actually been a fantastic success. The stadium is doing brilliantly, it had a brilliant summer.
"It has a long-term viable future, with Premier League football at the heart of the deal.
"There are stadiums like that which are totally moth-balled, that don't have any real activation. Go to Athens, Beijing… this has been a great success and a good investment for London.
"I think rather than carping and being miserable, you should congratulate the LLDC on the deal they have done."
Brazil debacle proves Johnson's point
Johnson has a point, too.
And proof, if it were needed, that West Ham are in fact the saving grace for the £517 million venue, came from South America earlier this year.
There, Brazil's $900 million World Cup stadium is now being used as a parking lot despite forming the bulk of a $3 billion spend on new or heavily refurbished stadiums for last year's showpiece event by the Brazilian authorities.
That is despite officials reportedly promising the taxpayer-funded venues would continue to generate revenue for years, hosting concerts, football matches and other events.
A thankless task made viable by Hammers?
Re-purposing an Olympic venue is a often a thankless task, as most events could never compare to their original states of glory.
But West Ham will get as close as you can get, hosting regular matches in the most watched football league in the world.
The warning signs were there for all to see with the likes of the abandoned Athens (2004) and Beijing (2008) stadia offering haunting examples of how the billions spent can go shamefully to waste.
Surely throwing away all the money that was spent on the Olympic Stadium in the first place by tearing it down or leaving it to rot would be a real crime. and it must be remembered West Ham will only have the stadium for 25 days a year.
The LLDC have the other 340 to maximise its potential financially.