Thousands of home carers could receive a pay boost after a tribunal ruling on payments for travelling between appointments.
Unions have long called for workers not to lose out on wages when they are driving from one patient another.
An employment tribunal found contractors commissioned by Haringey Council in North London breached pay rules.
The Government’s National Living Wage is £8.72 an hour, falling to £8.20 for those aged between 21 and 24, and only £6.45 for those aged 18 to 20.
Unison said the dispute against three private care firms centred over unpaid time carers spent travelling between people’s houses – despite the staff having to get from one home to the next to complete their job.
The workers had been hired on zero-hours contracts to look after elderly and disabled residents in their own homes.
Unison said this meant the workers could earn well under half the legal minimum hourly rate – despite working for up to 14 hours a day.
The judgment said travelling and waiting time of up to 60 minutes between appointments should be treated as working time.
This will give other carers a “clear method of calculating how much they are owed”, workers’ leaders said.
Unison believed home care workers on similar pay rates will “now feel empowered to challenge any employers who fail to pay them correctly.”
The claimants – most of whom are women – will receive an average settlement of around £10,000 each, Unison said.
General secretary Dave Prentis said: “This ruling sends a message to other care bosses that it’s completely unacceptable to pay staff illegal poverty wages.
“The Government too must get tougher with employers so there’s an end to these law-breaking practices.”
He added: “This is a major victory for these dedicated workers who dared take on their employers.
“Their long struggle is nothing short of heroic.
“It’s time the skills and experience of care staff were respected instead of them being underpaid and undervalued.
“The pandemic has proven just how vital they are in looking after the most vulnerable in society and keeping the care system running.
“These are the very same care staff who were applauded during the lockdown.
“They shouldn’t have to work in a system that breeds such awful treatment.”
Unison called on the Government to finally end the practice of employers denying care staff wages for time spent travelling between visits to the sick and elderly.
The union demanded a National Care Service to help prevent such practices – a bid that will be debated today at the Trades Union Congress.
A Department of Health and Social Care spokeswoman said: “We are very clear that social care workers must be paid at least the National Minimum Wage, with those over 25 earning at least the National Living Wage, and they should be paid for the time spent caring for clients, travelling to appointments and waiting for them to start.
“We know there is a need for a long-term solution for social care and are looking at a range of proposals as part of our commitment to bringing forward a plan that puts the sector on a sustainable footing for the future.”