The high-flying barrister is expected to meet ordinary people and go door-to-door making the case against Scottish independence.
A Labour source said she was keen to campaign on the issue because it is "something she cares about". The move is widely seen as a test run for her having a big role in Labour's 2015 campaign.
Last year she poked fun at the traditional image of a politician's wife, telling a group of youth activists at Labour's annual conference in Brighton "that I am in fact more than a dress".
And last night she joined her husband in Glasgow at the opening ceremony of the Commonwealth Games.
The Labour leader has said he does not want to "countenance being Prime Minister without Scotland".