Abayomi Olowo, 48, of Harrow, north-west London was jailed for four-and-a-half years and Ayodele Odukoya, 42, of Romford, Essex was sentenced to three years and nine months.
Six other people, including two women, were cleared by jurors of money laundering charges in relation to the fraud.
The convictions and sentencing come after Southwark Crown Court was told a gang of fraudsters conned the ODA out of £2.3m.
A third man Ansumana Kamara, who was the ringleader behind the fraud, pleaded guilty to a series of money laundering charges in 2010 and was sentenced last year to three-and-a-half years in jail.
He pretended to be Skanska’s finance director and wrote to the ODA with a change of account details ahead of a bank transfer.
After the money was paid into the accounts of his bogus law firm, he set about distributing large amounts to his accomplices, before attempting to wire a cheque for £2m to Nigeria.
But staff at the money transfer bureau grew suspicious and stopped the cash being sent overseas. The authorities were able to recover it before it was too late.
Attempts were also made to defraud firms that had contracts with Skanska, including Dorset County Council, Network Rail and Universal Builders Supply.
Judge Martin Beddoe, sentencing Odukoya and Olowo, said: “As the jury has found, both of you were ready and willing participants in the scheme to launder £2.3m stolen from the Olympic Delivery Authority.”
An ODA spokesman said: “We are pleased that this case has now reached a conclusion.
“The vast majority of the money, around 95%, was recovered although we now hope that the remaining £68,000 can be retrieved through further investigation by Operation Podium.
“Our payments system was reviewed and strengthened immediately after the incident to further limit the risk of fraud.”
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