The social care sector could face a shortfall of a million workers in the next 20 years, according to a report.
The system for adults in England faces a gap of 200,000 care workers by the end of this parliament due to restrictions on immigration and a failure to attract British workers, it said.
The report, from the charity Independent Age and the International Longevity Centre - UK (ILC-UK), warned this figure will grow unless efforts are made to recruit more overseas staff and retain those already working.
Almost one in five adult social care workers (18.4%) in England were born outside the UK, including 150,000 working in residential care homes.
People from outside the EU account for the largest percentage of migrants working in adult social care - around one in every seven care workers.
Experts behind the report warned that almost one in 20 (4.8%) positions in adult social care in England are vacant - nearly twice the rate in the UK's labour force as a whole.
They said the sector was already under immense pressure due to funding cuts to social care and an increasingly ageing population.
Simon Bottery, director of policy at Independent Age, said: "Without action, there is a real risk of care services worsening as providers fail to fill job vacancies and staff struggle to cope with increasing demand.
"That can only be bad news for the older people who rely on these services to carry out basic tasks like eating and dressing.
"We need to recognise the current reliance of social care on migrant workers and make it easier for them to work here but also look to the sector's longer-term future.
"The Government must use the upcoming spending review to invest in social care so it can attract more UK workers, while at the same time exploring new ways of caring for our ageing population in the future."
Ben Franklin, head of economics of ageing at ILC-UK, said: "Enabling migrant workers to fill workforce gaps is one part of the solution, but it is no silver bullet. We need to ensure that the sector is able to attract more UK and foreign-born workers alike.
"This will require a substantive shift in the direction of policy as well as a change in public perceptions about what working in care is like."
A Department of Health spokeswoman said: "We have provided £3.2 billion in transfers from the NHS to social care to ease pressures and the National Living Wage will help attract workers to the sector.
"Working in better, smarter ways is key to dealing with our growing ageing population. We are enabling this through our £5.3 billion Better Care Fund which is getting local NHS and councils working together to keep people well and living independently."