Tony Blair's former spin doctor Campbell, a leading campaigner for a second referendum on Brexit, said he was "sad and disappointed".
It came following the party's bruising performance in the EU election, losing out to the Brexit Party and the Liberal Democrats.
A Labour Party spokesman said "support for another political party or candidate is incompatible with Party membership".
Campbell, one of the key players in the New Labour era, insisted there was "plenty of precedent" of members voting for other parties or causes.
The 62-year-old said there was a difference in the swift way his situation had been dealt with compared to "the way anti-Semitism cases have been handled".
Announcing the news on Twitter, he said: "Sad and disappointed to receive email expelling me from @uklabour – particularly on a day leadership finally seems to be moving to the right place on Brexit, not least thanks to tactical voting by party members, including MPs, councillors and peers who back @peoplesvote_uk."
Mr Campbell added: "I am and always will be Labour. I voted Lib Dem, without advance publicity, to try to persuade Labour to do right thing for country/party.
"In light of appeal, I won't be doing media on this. But hard not to point out difference in the way anti-Semitism cases have been handled."
Labour's leading pro-Corbyn faction Momentum tweeted: "Alastair Campbell's 'sexed up' dossier started the Iraq war and left a million dead. Being kicked out of the party is the least he deserves."
SPIN DOCTOR: Alastair Campbell was the man behind Tony Blair (Pic: GETTY)
“I am a Labour Party supporter and I voted because I think Labour need to get the message”
Yesterday, Campbell admitted he voted for the Lib Dems – who ended up finishing second in the election with 18.5% of the vote, as opposed to Labour's third with 14.1%.
He said: "I voted for the Liberal Democrats. But I am not a Liberal Democrat. I am a Labour Party supporter and I voted because I think Labour need to get the message.
"And I think they are going to get the message, particularly in the more Remain areas.
"We, the Labour Party, have been losing four times as many votes to the Liberal Democrats, Greens etc than we have to the Brexit Party."
CAMPAIGN: Alastair Campbell plays bagpipes at a pro-EU rally in Westminster (Pic: GETTY) Related Articles
PEOPLE'S VOTE: Alastair Campbell wants to stop Brexit amid the divisions rocking Britain (Pic: GETTY)
He added: "Yes, it's true that some Labour supporters will be saying I'm not voting Labour because I think they are too pro-Remain, but Labour are getting absolutely destroyed.
"I think there's a big danger that Jeremy Corbyn, Len McCluskey, Seumas Milne, Karie Murphy – the minority in this party who are now driving this policy – I think there is a danger that, no matter how much the Tories implode, I think there is a danger that the Labour Party will go to oblivion."
Campbell's explusion comes as Labour is moving towards a "clearer line" on Brexit, Diane Abbott insisted, amid heavy losses at the EU elections.
The shadow home secretary said there was "no inherent contradiction" between respecting the result of the 2016 referendum and having another poll, as calls for the party to fully throw its weight behind a so-called People's Vote intensified.
ALL SMILES: Jeremy Corbyn suffered a brusing performance in the EU elections (Pic: GETTY)
Labour deputy Tom Watson, shadow chancellor John McDonnell and shadow Brexit secretary Sir Keir Starmer have all called for a shift in stance to back a second referendum over Jeremy Corbyn's preference for a general election.
Mr Watson was among members of Mr Corbyn's shadow cabinet calling for him to change tack and move away from his compromise position on Brexit, which seemed to have been punished by voters leaving the official opposition in third place.
"We've lost many hundreds of thousands, if not millions of potential votes in that election because we got it wrong," he told the BBC.
"The time is now to show some humility, to listen and to move very, very quickly."
Mr McDonnell also moved to corner his boss, alongside Ms Abbott, saying Labour should back Remain in another poll.