UBS, Goldman Sachs, Barclays and Bank of America Merrill Lynch will work with the Government, the Royal Mail and advisers to prepare for the controversial sale. Opponents of the sell-off said the banks were set to make £30 million.
Business Minister Michael Fallon said no final decision had been made on the structure of the sale, adding that all options remained open.
He said: "Preparations for the sale of shares in Royal Mail continue to build momentum and these appointments represent another important step towards a sale of shares this financial year.
"While all options for the form of sale remain open, it is important that we are in a position to move ahead swiftly with our chosen route once we take the final decision.
"Given the lead time and preparatory work involved in readying an IPO (initial public offering), the appointed banking syndicate will work to make sure we are ready to proceed when the time comes and will be able to deliver strong, high-quality investor demand to ensure a successful IPO for the taxpayer and for Royal Mail."
Billy Hayes, general secretary of the Communication Workers Union, which has warned that postal services will be hit by privatisation, said: "The Government is wasting significant sums of taxpayers' money on a deeply unpopular and unnecessary privatisation agenda.
"Throwing public money at banks to flog a national asset is poor use of public funds. This Government has got it wrong on privatising Royal Mail."
Mario Dunn, of campaign group Save Our Royal Mail, said: "We learn today that banks are set to make up to £30 million when the Government sell off Royal Mail. Once again consumers will lose out when prices rise and deliveries are reduced, but banks make millions."