Another seven million of the coins, which was unveiled by Chancellor Sajid Javid on January 25 and inscribed with the words "peace, prosperity and friendship with all nations", will enter circulation later this year, the Metro newspaper said in a report.
The Royal Mint has produced versions for sale which range from 10 pounds for an uncirculated 50p to 945 pounds for a limited edition gold coin.
The Mint said it was the fourth time it has been involved in the production of a commemorative coin to mark the UK's relationship with the EU.
It produced a coin when the UK joined the European Economic Community in 1973, created a design for the single market in 1992, and marked the UK's 25th anniversary of joining the EU in 1998.
The coins are dated January 31, which according to Javid marked the beginning of a "new chapter".
Javid had originally ordered production of the celebratory coins in advance of the previous departure date of October 31, 2019, the Metro newspaper reported.
But the Brexit delay meant about a million coins had to be melted down and the metal put aside until a new exit date was confirmed.
The idea for a Brexit commemorative coin was first pitched by former Chancellor Philip Hammond, although he reportedly planned a batch of just 10,000 pieces.
The UK will leave the EU at 11 p.m. on Friday.
( With inputs from IANS )