The campaign to keep Britain in the EU is formally launching with a warning that exit would be a "leap in the dark" and cost every household thousands of pounds.
Unveiling his team fighting for an "in" vote at the looming referendum, businessman Lord Rose will brand those wanting to leave the union "quitters".
He will also dismiss the idea that there is a "patriotic" case for withdrawing from the EU.
Europhiles and Eurosceptics have been drawing battle lines as they gear up for what could be a long and attritional campaign. David Cameron has promised to hold the decisive vote by the end of 2017 - but some have suggested it could happen as early as next spring.
Former Marks & Spencer chief Lord Rose will announce the membership of the board of the new Britain Stronger In Europe group at an event in London later.
It features representatives from all sectors of UK society - including former chief of the general staff Sir Peter Wall, West Ham United vice-chairwoman and Apprentice star Karren Brady, and June Sarpong, a panellist on ITV's Loose Women.
Jude Kelly, the artistic director of London's Southbank Centre, has also signed up, along with Liverpool University vice-chancellor Janet Beer and political grandees like Lord Mandelson and Danny Alexander.
Former prime ministers Sir John Major, Gordon Brown and Tony Blair are supporting the drive, and other political "champions" include ex-Labour frontbencher Chuka Umunna, Green Party MP Caroline Lucas, and Tory Damian Green.
Lord Rose will tell the event that he believes the EU has to change.
"Those of you who know me will know that I am not an uncritical fan of the European Union. Far from it. That's why I signed a letter arranged by Business for Britain calling for reform of the EU," he will say.
"Wanting reform, however, is not the same as wanting to leave. Make no mistake: I am part of this campaign because I believe that we are stronger, better off and safer inside Europe than we would be out on our own."
Lord Rose will reject the idea of a choice between patriotism and EU membership.
"To claim that the patriotic course for Britain is to retreat, withdraw and become inward looking is to misunderstand who we are as a nation," he will say.
"I will not allow anyone to tell me I'm any less British because I believe in the strongest possible Britain for business, for our security and our society."
He will cite CBI estimates that the benefits of trade, investment, jobs and lower prices mean membership is worth £3,000 per year on average to every UK household.
"When you consider that our annual contribution is equivalent to £340 per household, our contribution to the EU is an investment on which British families get a 10-to-one return," he will add.
Lord Rose will say leaving the EU is "just not worth the risk".
"The quitters have no idea whether we would be able to access Europe's free trade area, or what the price of admission would be," he will say.
"The quitters have no idea how long it would take to renegotiate existing trade deals or how difficult it would be to negotiate new ones outside the EU, let alone how inferior the terms would be.
"The quitters cannot guarantee that jobs would be safe and prices wouldn't rise.
"The quitters cannot explain how we could stop free movement and simultaneously keep our access to the world's largest duty free market."
However, Eurosceptics were out in force on political programmes over the weekend making the case for exit. Ukip leader Nigel Farage suggested the crucial issue would be whether Britain could control its own borders and remain in the EU.
He played down rifts within the out campaign, insisting he supported both the Leave.EU group masterminded by Ukip donor Arron Banks and the Vote Leave group.
Whichever group is designated the official out campaign by the Electoral Commission will enjoy significant advantages, including higher spending limits, campaign broadcasts, free mail shots and public funding of up to £600,000.
Mr Farage argued the two organisations were "complementary", with one targeting the grass roots and the other dominated by "Westminster" figures.
The Ukip leader also suggested that London mayor Boris Johnson could be persuaded to take a prominent role in the campaign for Brexit.
Mr Johnson has so far been careful to support Mr Cameron's position of waiting to see the outcome of the current renegotiation before taking sides, but many believe his private views are more hardline.
"We might just get him," Mr Farage told Sky News' Murnaghan programme. "We might just get him and he is a recognisable figure. That would be good news."