The campaign organisation's analysis of the Labour Force Survey (LFS) and Family Resource Survey (FRS) found millions are earning less than the Real Living Wage (£10.85 per hour in London, and £9.50 elsewhere).
The volatile pay and hours, non-permanent contracts and low-paid self-employment experienced by these workers is having a significant negative impact on their health, family lives and future plans.
Workers' rights in the UK:
Joe Richardson, research manager at the LWF, said the findings brings to life the harsh reality of working life for many people across the country.
Speaking to HR magazine he said: "Earning below the real Living Wage means workers will not have enough income to meet living costs, but work insecurity brings about further reductions to income and increased living costs, a double penalty for the nation's low paid.
"Insecure work sky-rocketed in the aftermath of the 2008 Financial Crisis, and it is crucial that the economic fallout from COVID-19 does not accelerate this process further."
Almost half (42%) of those surveyed said they have experienced unexpected cancellations of shifts. Of those, 28% receive no payment and 90% get shifts cancelled without full pay.
A quarter (25%) said they had to pay higher travel costs due to short notice for working hours, shifts or work schedules, and 23% had to do the same with childcare costs.
Angela Rayner, Labour’s deputy leader and shadow secretary of state for the future of work, said the findings show too many people are experiencing unpredictable and insecure work.
She said: “The scourge of insecure work and poverty wages that is blighting millions of lives is proof that our economic model is broken.
“A job should provide security, dignity and a proper wage that you can support your family on.”
Rayner said a new deal for working people is needed, and promised Labour will deliver an immediate living wage of £10 an hour is elected.
“The party will also give all workers full rights from day one on the job so that everyone has the right to sick pay, the minimum wage, and holiday pay,” she said.
In addition to the overall level of low-paid work in the UK, significant differences were found based on ethnicity, age and the sector people work in.
A quarter (25%) of Bangladeshi workers experience low-paid, insecure work, the same as for Pakistani workers.
Meanwhile, 13% of Black workers face low-paid insecure work, compared to 10% of white workers.
Those aged 70 or above were found to be the age group most likely to be in low-paid insecure work (35%), with young people (16–19-year-olds) the second most likely (27%).
Danny Harmer, chief people officer at Aviva, said businesses need to provide jobs that treat and pay people fairly.
She said: “We should not underestimate the impact unstable and unpredictable hours have on the individual, and on their families too.
“Signing up to Living Hours stands for providing financial clarity and certainty. That means happier and healthier colleagues which is good for customers, business and society.”