In a keynote speech to his party's conference, the Labour leader will not use dry facts to make the case for the Union, but a personal anecdote involving a shop worker from Glasgow.
He will recount how Cathy Murphy, attending the Labour conference in Liverpool two years ago, was taken ill.
He will say: "The doctors feared the worst. They thought she would die and called her family down from Glasgow, but somehow they managed to stabilise her condition."
Weeks later, Ms Murphy underwent a 14-hour operation at the Liverpool Broadgreen Hospital to save her life; she pulled through and eventually returned home to Glasgow.
Mr Miliband will explain: "She comes back to Liverpool every six months for a check-up. And you know what? The doctors and nurses don't ask whether she lives in England or Scotland.
"They know she is Scottish - and British. Cathy is with us today, back as a conference delegate."
Mr Miliband will also set out his vision for a "one-nation economy", announcing a decision, if elected to power, to halt the planned cut in corporation tax for big businesses in 2015 and using the money to cut business rates for more than one million small firms.
As business rates are set in Scotland for Scottish firms, the policy, it is estimated, will mean more than £100 million being taken from large companies and handed over to the SNP Government.
Meanwhile, as the Labour conference continued to be overshadowed by the revelations of Damian McBride, Gordon Brown's former spin doctor, the ex-Prime Minister stonewalled questions about his claims as Mr McBride turned up to defend publicising his explosive memoirs.