Speaking at the UK Labour Party conference she will set out her plans to build on a "referendum win" for the No side.
In a speech denounced by the SNP as a complacent blunder, Lamont will say she expects to be "warmly celebrating" the survival of the union in a year's time. Former Labour chancellor Alistair Darling, the chair of the Better Together campaign, last week expressed his frustration at people in the unionist camp taking a No vote in next year's referendum for granted.
But Lamont will say today: "This is a historic day. It marks one year to go until I get to stand here and warmly celebrate with everyone in this room that Scotland has chosen to reaffirm its place in our United Kingdom and elected to continue working in partnership with our neighbours. I expect to be standing in front of a UK Labour conference audience as Scottish leader of a party that has persuaded most Scots that our future lies in partnership with our neighbours."
Lamont's contribution is one of many touching on the referendum this week in Brighton.
Shadow Scottish secretary Margaret Curran will speak on the subject today, while Jim Murphy and Douglas Alexander, the shadow defence and foreign secretaries, speak tomorrow. Shadow Chancellor Ed Balls and Labour leader Ed Miliband will also raise the issue.
SNP MSP Linda Fabiani said: "Whoever wrote this speech for Johann Lamont has made a very bad blunder by taking the people of Scotland for granted - which is exactly what Labour did before the 2011 Holyrood election.
"We will be campaigning extremely hard for the people of Scotland to have the best of both worlds - an independent Parliament with the powers to make the wealth of Scotland work for the people, and a relationship of equality with our friends and neighbours south of the border."
Ahead of the conference, Miliband promised to help families by pledging a guaranteed childcare for primary school pupils and reversing the coalition's "bedroom tax".
He also said he would "strengthen" the minimum wage by making big industry pay staff more.
Miliband made the pledge as he stood on a box in the centre of the city to address passing shoppers and party supporters. He said: "Abolishing the bedroom tax. Strengthening the national minimum wage. Childcare there for parents who need it, that's what I mean by tackling the cost of living crisis at this conference. That's what I mean by a government that fights for you."