Three former prime ministers, the ex-head of the army and a panellist on Loose Women are joining the push to stay in the EU.
The "in" campaign, expected to be called Britain Stronger in Europe, has the backing of Sir John Major, Tony Blair and Gordon Brown.
Chaired by ex-Marks & Spencer boss Lord Rose, the board includes former chief of the general staff Sir Peter Wall.
Other members have backgrounds in the arts, while former T4 presenter June Sarpong - now a panellist on ITV's Loose Women - has been drafted in to help appeal to younger voters.
According to the Sunday Times, she is likely to front the campaign's advertisements in cinemas.
Baroness (Karren) Brady, the West Ham United vice-chairwoman and Apprentice star, will have a central role, alongside Innocent drinks co-founder Richard Reed.
Jude Kelly, the artistic director of London's Southbank Centre, has also signed up, along with Liverpool University vice-chancellor Janet Beer and former TUC general secretary Brendan Barber.
Longstanding Europhile politicians such as Lord Mandelson, Sir Danny Alexander, Damian Green, and Green MP Caroline Lucas are joining.
Writing in the newspaper, Lord Rose accused those who want to leave the EU of "fantasyland" economics and branded their claims that Britain would thrive outside "bravado, not patriotism".
Quitting the union would cost every family £3,000 a year, he warned.