In a survey carried out by Gingerbread, two-thirds of working single parents said finances are a constant struggle while one in 10 said they were not coping financially.
Their report, called Paying the Price: The Long Road to Recovery, found lone mothers and fathers are twice as likely than other workers to be working in low-paid jobs.
The charity, which questioned some 2400 single parents, found little evidence of an economic upturn in the lives of those who are working or "desperately trying" to break into the jobs market.
It called on the Government and employers to better support them, including offering in-work financial support and job security to help them out of poverty.
Gingerbread chief executive Fiona Weir said: "Single parents are working incredibly hard to provide for their families, but all too often they are barely keeping up with the costs of the essentials.
"There is little sign of an economic recovery for parents who have had to go without another meal and face the nagging, gnawing worry of bills marked 'final warning'. Our report shows that for single parent families, work isn't a golden ticket out of poverty."
Single parents reported feeling "disadvantaged", with few part-time or flexible jobs on offer for parents needing to juggle childcare with work. One in six said they worked multiple jobs, while a quarter had increased their working hours. Ms Weir added: "Single parents are the sole earners for their family, so it's absolutely vital that, when they go out to work, their job pays a decent wage and offers them stability. Without action from government and employers on in-work financial support, low-pay and job security, too many single parent families will remain trapped in poverty."
The report follows the release of figures, which found a rise in child poverty for single parent households where the parent works full-time, climbing from 17 per cent in 2011-12 to 22 per cent in 2012-13.