The Prime Minister had claimed the contracts which are currently subject to a legal challenge were in the public domain.
However, a High Court order published on Friday has now revealed the government had only published “608 out of 708 relevant contracts”.
The order, by judge Mr Justice Chamberlain, says: “The defendant has published 608 out of 708 relevant contracts for supplies and services relating to Covid-19 awarded on or before October 7, 2020.
“In some or all of these cases, the defendant acted unlawfully by failing to publish the contracts within the period set out in the Crown Commercial Service’s Publication of Central Government Tenders and Contracts: Central Government Transparency Guidance Note (November 2017).”
But Mr Johnson had reassured MPs otherwise in Parliament on February 22, saying: "All I will say is that the contracts are there on the record for everybody to see.”
The revelation comes shortly after a High Court judge also found UK health secretary Matt Hancock had also acted unlawfully by handing out contracts without publishing details in a timely way.
Both cases were brought by the Good Law Project, which says the latest document from the court confirms the Prime Minister misled MPs.
In a statement, it said: "Remarkably, the Judge’s Order is based on government’s own figures – so at the same time as Johnson was falsely reassuring MPs, government lawyers were preparing a statement contradicting him – revealing 100 contracts and dozens of contract award notices were missing from the public record.
“Government has not only misled Parliament and placed inaccurate information before the court, it has misled the country."
Labour’s shadow Scotland secretary Ian Murray said: “It is unforgiveable for Boris Johnson to mislead the Parliament and the nation on this matter.
“Throughout the pandemic, the Tory government has doled out contracts to its friends and shown complete disregard for the rules and processes in place.
“This cronyism must stop and heads must roll.”
The controversy comes at a time Mr Johnson’s Scottish Tory MPs are trying to force Nicola Sturgeon to resign after accusing the First Minister of misleading Parliament.
The UK Government did not deny that Parliament had been misled.
A spokesperson said: “We have been working tirelessly to deliver what is needed to protect our health and social care staff throughout this pandemic, within very short timescales and against a backdrop of unparalleled global demand.
“This has often meant having to award contracts at speed to secure the vital supplies required to protect NHS workers and the public.
We are committed to publishing all contracts and to date have published 99 per cent of these in the Official Journal of the EU and we are working to publish outstanding contracts as soon as possible.
“As the 2020 NAO report recognised, all of the NHS providers audited were always able to get what they needed in time, thanks to the effort of government, the NHS, Armed Forces, civil servants and industry, who delivered over 8.8 billion items of PPE to the frontline at record speed."