Tens of thousands of people will join the biggest demonstration for years on Saturday calling for a "new deal" for workers and public services.
Union members and campaigners from across the UK will travel to the event in central London, organised by the TUC, which is calling for a higher minimum wage, a ban on zero hours contracts and more funding for the NHS, education and other public services.
Jeremy Corbyn will be among the speakers addressing frontline workers including nurses, ambulance crews, postmen, teachers, civil servants and cleaners after they march through the capital.
To mark the event, the TUC published data which it said showed that workers were suffering the longest squeeze on wages in modern history.
A decade on from the financial crisis, real wages are worth £24 a week less than in 2008 and are not forecast to return to pre-crash levels until 2025, said the union organisation.
The TUC said the current stretch of wage stagnation was the worst for 200 years.
By 2025 the average worker will have lost out by around £18,500 in real earnings, it was estimated.
TUC general secretary Frances O'Grady will tell marchers: "UK workers are suffering the worst pay squeeze for two centuries. It's taking wages longer to recover from this crash than from the great depression and Second World War.
"This means families are struggling to get by. Millions of kids are growing up in poverty despite having parents in work. Mums and dads are skipping meals and turning to dodgy lenders to make ends meet.
"That's why tens of thousands are marching today for a new deal for working people. We need great jobs in every region and nation of the UK, and higher wages for all workers, not just the bosses."
It is set to be the biggest demonstration since the last big TUC demonstration in London four years ago.
Jeremy Corbyn is expected to tell the rally the Labour Party will always "proudly support" working people coming together and organising to transform their workplaces and the country.
He will say that talking to workers yesterday, he heard tales of "low pay, bad conditions, abusive management, insecure hours and victimisation if you try to stand up for yourself and your fellow workers".
Mr Corbyn will continue: "Those workplace issues are central to everything we do. We are proud that they are Labour priorities. And we don't shy away from telling it how it is - that many of the rich and powerful dodge taxes and a lot of bosses exploit their workers.
"That's why in government, we will give workers and employees more power at work, by strengthening their rights and freedoms to organise together to improve their lives."
He will add: "It's time for a fundamental shift in power in our country - from the few to the many - and that is exactly what the next Labour government will deliver."