He said that he had decided to make his gift public although he was under no obligation to do so.
"I'm proud to be a longstanding supporter of the Labour party and the Labour government," he added.
Lord Hamlyn said that the £2m gift was "one of several large donations I have made to political and other causes."
His disclosure comes after days of mounting pressure on Labour to reveal the source of the cash, which was given before new rules that would have required disclosure come into effect next month.
Lord Hamlyn, who was appointed CBE in 1993 by the Conservative government for charitable services, said in his statement: "Having followed the debate on donations to the Labour party for the past few days, I'm happy to make public that I recently made a £2m donation to the party...
"I believe anyone who wants to see Britain develop as a strong economy and a fairer society has a vested interest in seeing the re-election of the Labour government.
"Under the existing legislation, I'm under no obligation to disclose the sum I have donated, but I'm happy to do so. I have said nothing until now because I'm overseas recovering from serious illness. For that reason I will be making no further comment.
"I make no apologies for supporting the Labour party in this way. Our democracy depends on vibrant political parties and, for years, the Conservatives had a virtual monopoly on large donations from individuals.
"I'm glad that has changed and I'm proud of the role I have played in helping the Labour party."
Friends said that Lord Hamlyn was suffering from pneumonia, has Parkinson's disease and is recovering from cancer.
Cabinet office minister Lord Falconer, a close ally of Prime Minister Tony Blair, told ITN: "It was this government that introduced changes which require the naming of donors. People who make donations before that - it's matter for them to decide if they make their names public.
"Lord Hamlyn has made his name public. I know he has been ill, so I think it's rather unkind to criticise him for only allowing his name to come forward at this moment."
Labour party chairwoman Maggie Jones said: "Paul Hamlyn is a respected businessman and a well-known supporter of the Labour party. The party is proud of the fact that people like him support us and that we are able to attract substantial donations from business people.
"As promised, the Labour party has made a number of changes to tighten the rules on party funding. Tony Blair was the first political leader to disclose a list of donors over £5,000.
"This Labour government has legislated for the greater transparency we promised. From February 16, when the new law comes into effect, the size of donations, as well as the names of donors will be published.
"Over the past few years, the Labour party has received a number of substantial donations, and it would be quite wrong if the Labour party alone was under an obligation to apply new rules retrospectively.
"If those rules are to be made retrospective, then they must be made retrospective for everyone, including the Conservatives - who still have not told us how they funded the 1997 election campaign."
Talk about it
Should political donors be named?
Related stories
Profile: Paul Hamlyn
January 2: Labour may ask £2m donor to go public
January 1: Pressure on Blair to name £2m donor
September 9 1999: Anger over minister's £2m donation to Labour
Useful links
Labour party
Committee on standards in public life
Paul Hamlyn Foundation
Hamlyn Books
Octopus publishing group
