Ms Dugdale will accuse the SNP of focusing on the constitution at the expense of Scotland’s flagging economy and public services at the event in Edinburgh.
Labour have fallen behind Ruth Davidson’s Conservatives, who have been successful in appealing to the pro-Union vote in Scotland.
Both Ms Dugdale and UK party leader Jeremy Corbyn have stepped up their opposition to independence before today’s launch in Edinburgh.
The manifesto states: “Scottish Labour will never support independence, because we believe that together we’re stronger.”
It follows a similar commitment in Labour’s UK manifesto last week which confirmed the party’s opposition to both another “divisive” independence referendum and separation itself.
Ms Dugdale is launching the document on the back of a difficult campaign which has seen Labour struggling in a distant third place behind the SNP and the Tories in the polls and internal strife after a rebellion among councillors in Aberdeen who were suspended after forming a coalition with the Tories.
She is hoping the manifesto launch will send out the message to Scots that Labour can be trusted to fight independence as strongly as the Conservatives.
She says in her manifesto foreword: “Labour is the only party which knows it is the power of the whole UK working in partnership which benefits the many, not the few – that is at the root of our belief that together we’re stronger.
“That is why Labour opposes independence and a second divisive independence referendum. Independence is not the answer to dealing with Scotland’s flagging economy or our pressured public services.
“The SNP has one focus – independence. Labour will campaign tirelessly to ensure that the desire of the majority of Scots to remain part of the UK is respected.”
Prime Minister Theresa May last week branded Mr Corbyn weak on the independence issue after he indicated in an interview last year that he would be “absolutely fine” with another referendum.
Mr Corbyn has since made it clear he would oppose such a move and warns again today that nationalism is not the answer to society’s ills.
He states in his foreword to the manifesto: “In Scotland, child poverty is increasing, the number of those working but still classified as poor is at its highest level since devolution and health inequalities stubbornly persist.
“Rather than tackle poverty, the SNP obsesses over another reckless referendum that threatens people’s futures.
“Labour is opposed to independence because it would inflict turbo-charged austerity on the Scottish people.
“We will stand firm in our opposition to a second referendum because we know that together we’re stronger and unity is still our strength.
“Historically, it has been the solidarity and common endeavour of our Labour and trade union movement that has transformed the lives of the many, not the few, in our great country.
“Just as it has always been the case, only our movement offers the hope and the contemporary solutions to society’s problems. Nationalism, in whatever form, does not.”
Labour’s manifesto will pledge to introduce a Bill banning MSPs from holding paid second jobs after it emerged that some receive up to £130,000 in outside earnings.
Lothians MSP Neil Findlay will bring forward proposals to consult on restricting the time and earnings of paid second jobs in an effort to “restore faith” in politics.
Labour will also set out plans to extend breakfast clubs into every primary school to give children a healthy start to the day, as well as a ban on onshore fracking to protect the environment.
There will also be measures to improve access to sanitary products to tackle “period poverty” and plans to scrap the Offensive Behaviour at Football Act.
Ms Dugdale added: “It’s a manifesto for delivering change here in Scotland. Through Members’ Bills in the Scottish Parliament, Labour can help to grow our economy, restore faith in our democracy and give people a fair chance in life.”