The Boomtown Rats singer made an impassioned plea to Scottish voters ‘not to break up the family’ at a London rally.
Irish and Scots have ridiculed the Dublin born singer, who accepted a honorary knighthood off the Queen for his charity work.
The Live Aid organizer has been heavily criticized for his remarks at the ‘Let’s Stay Together’ gathering in Trafalgar Square.
Comedians Eddie Izzard, Al Murray and Jenny Colgan and presenter June Sarpong also urged a 'No' vote in Thursday’s referendum.
But Geldof caused a storm on social media when he described England and Scotland as ‘the closest of cousins.’
The Daily Telegraph reports that Geldof said: “I’d just like to tell everybody in Scotland we’re all f****** fed up with Westminster and it’s even more frustrating for us because we don’t even get to do the argument that you’ve begun.
“This argument needs to be had among us all, you can’t selfishly resolve it amongst yourselves by taking an easy opt-out clause.
“Before there was a United States, before there was a United Nations, before there was a united this, that and the other there was a United Kingdom and it was an extraordinary meeting of very different minds of two extremely close cousins.
“And what a construct this thing is. Because Scotland is a feeling. England is a feeling. Wales is a feeling, Ireland a feeling.
“But the United Kingdom is one of the greatest ideas for the modern age. Between the native genius of the Scots and the pure pragmatic drive of the English we made a world beater.
“The pity of this is that we are the closest of cousins – when one of our blood spills then it all spills. There is such thing as a big glorious no. No is not always a negative.”
The report says Geldof later added: “Obviously a lot of people will be saying that we want to break up, but I just want to know why?
“The UK is a phenomenal modern idea, invented by the Scots. They invented our age and the 21st century really needs to be reinvented, which I think is at the heart of the argument.
“We are all fed up with Westminster but they’ve got an option and we should be able to work out, together, a new constitution.
“But breaking up one of the most genius ideas of the modern political times is not the way to go. 82 percent of people in England want Scotland to stay, that should show that this is a union that works.”
Twitter went into overdrive at the notion of an Irishman backing British unity.
Ian Paisley may no longer be with us, but a new defender of the Empire has arisen. His padawan, Bob Geldof.— Fachtna Kelly (@FachtnaK) September 15, 2014
Dear Scotland, we apologise for Bob Geldof. - the Irish— Michael McBride (@IsMiseMick) September 15, 2014
Read more: Will Scottish see through English panic response to independence?
Geldof is due to play a date in Glasgow in October with the Boomtown Rats and hopes Scotland will still be part of the Union.
In another interview, he stated: “Nationalism is a very dangerous political animal. I know this – I’m Irish. It’s a cheap political trick which twists the understanding of who we are.
“I completely understand the emotional impulse towards independence. But always consider independence in inverted commas because what the f*** does it mean?
“We are entirely dependent on one another. None of us, in our private lives or our political constructs, are ever independent.
“The world is changing and needs different institutions, but not just removing ourselves from each other.”
With the referendum just days away, Geldof added:: “We’re down to the thin bones of the argument when people have started shouting at each other. People should be allowed to speak in any forum they like, be listened to and rebutted.
“That’s the way we do these things here, because ultimately modern civilization was invented between these two peoples.
“It’s only together, with a single shared sense of purpose, that we get to do things in the 21st century. There’s plenty to be done. Let’s get on and do it together.”