The philanthropist also attacked “13 years of bad decisions and reckless choices” by the Tories – saying the UK deserved better than the “self-obsession” shown by Rishi Sunak’s party.
The business intervention represents the latest blow for the Tories after grandee Ken Clarke threw his weight behind Ms Reeves as chancellor following a ringing endorsement from former Bank of England governor Mark Carney.
Mr Sunak a steady stream of desertions by top Tory donors and defections of business backers to Labour, with polls putting Sir Keir’s party on course for a general election victory akin to Sir Tony Blair’s landslide.
Ms Perrin, founder and director of the grant-giving foundation Indigo Trust, said: “I’ve never been more certain that the Labour Party is the best choice for our future.”
She told The Telegraph: “I believe Keir and Rachel are the best chance this country has of renewing our standing in the world. Every cause that I care about needs Labour in power if anything is going to improve.”
Ms Perrin, who has previously acted as government adviser under the Labour administrations of Tony Blair and Gordon Brown, said: “There is so much damage to be undone after 13 years of bad decisions and reckless choices.
She added: “Britain deserves better than the Tories’ self-interest, self-obsession and playing games with people’s lives.”
Her father Lord Sainsbury is believed to given Labour its largest-ever personal donation when he donated £3m earlier this year.
The former supermarket chair withdrew his financial support for the party during the Jeremy Corbyn era. The peer said he wanted “to see Keir Starmer become prime minister as soon as possible”.
The roughly £2m given by Ms Perrin to Labour in recent years puts her on the same level as Lubov Chernukhin, the Russian-born UK businesswoman who has donated just over £2m to the Tories.
Welcoming the latest big donation, a Labour spokesperson said: “Donors are coming back to Labour because they can see we are a changed party that is serious about delivering for working people with five missions to transform Britain.
They added: “The Labour Party is a changed party that will work hard to get Britain’s future back.”
Earlier this month Richard Huntington, the strategy chief at the Saatchi & Saatchi agency behind the pre-1979 “Labour isn’t working ads”– told The Independent that Britain needs saving from “five more years of stagnation, cruelty and despair”.
Frozen food chain Iceland’s executive chair, Richard Walker, became the latest Tory donor to withdraw his support last month, saying he was “open” to supporting Sir Keir.
Phones4U founder John Caudwell said he would not back the Tories after the “madness” of Mr Sunak’s U-turn on net zero – and that he was thinking of giving to Labour instead.
Another Tory donor, Philip Harris, founder of Carpetright, said the Conservative Party did not “deserve” to win the 2024 general election.