The Prime Minister's wife will join Labour's campaign in the Glenrothes by-election this week.
Sarah Brown will knock on doors and talk to voters in the Fife constituency.
She also plans to meet pensioners and young mothers during her day of campaigning in the town.
The revelation comes almost a month after she stepped on to centre stage at the Labour conference to introduce her husband's keynote speech to the party faithful.
A spokesman for Scottish Labour confirmed that Mrs Brown intends to visit Glenrothes later in the week.
He said: "She will be coming at some point this week. She will be knocking on doors, meeting pensioners and also meeting young mums."
Scottish Secretary Jim Murphy told the Daily Record: "Sarah's a real star. She will shine on the doorstep. Her decision is a real boost for our campaign. And it's a signal that Labour is fighting for every single vote."
The Prime Minister last week confirmed in a letter to Labour MPs and peers that he intends to campaign in the constituency, which is next door to his own Kirkcaldy and Cowdenbeath seat.
UK Health Secretary Alan Johnson is due on the campaign trail for Labour, joined by Cathy Jamieson, the party's health spokeswoman at Holyrood.
Labour is defending a majority of 10,664 in a seat made vacant by the death of MP John MacDougall, who lost his battle with cancer in August. Voters will go to the polls on November 6.
