Department for Work and Pensions figures show that 367 single-parent families had their benefits capped in Dacorum during February.
This was a rise of 70 per cent on the number capped in the same period last year, when 216 had either their housing benefit or Universal Credit payment reduced.
Altogether, 638 had their benefits capped in February this year, 374 more than a year previously – with 58 per cent of them single-parent families.
Across Great Britain, 200,000 households had their benefits capped during February, more than twice the 77,700 impacted in the same period last year.
That included 166,200 households with children, and 117,200 with single parents.
The benefit cap limits the total income a household can receive from certain benefits, and currently kicks in at £20,000 per year for families with children outside of London, and £23,000 for those in the capital.
The limits are lower for single adults and lone parents whose children do not live with them.
Money is taken away by reducing either their housing benefit or Universal Credit payments – although there is an initial nine-month grace period during which benefits will not be capped.
The DWP said the record number in February had been driven by a rise in Universal Credit claimants due to job losses linked to the Covid-19 pandemic last year.
According to Child Poverty Action Group, which wants the cap abolished, households impacted are losing out on an average £62 a week.
The charity said families were finding it hard to escape the cap due to a continued lack of jobs and unaffordable childcare.
Chief executive Alison Garnham said: "The benefit cap has always been an unjust punishment for families.
"Thousands more households who have lost jobs to Covid-19 are now subject to the cap even though in the pandemic it is much harder to find ways to replace their lost earnings and become exempt.
"Especially in areas with high rents, capped families are losing large amounts of social security support and that is disastrous for the children concerned."
Meanwhile, homeless charity Shelter said a government failure to review the cap had plunged many families into poverty and put them at risk of homelessness.
Chief executive Polly Neate said: "The cap means people whose incomes have been decimated by the pandemic cannot access enough financial support to cover their basic costs, like rent or food for their family."
In Dacorum, of the households to have benefits capped in February, the largest proportion – 315 families – had up to £100 taken off the weekly amount they receive, while around 210 had more than £200 removed.
The DWP said a review of the benefit cap will be carried out at "the appropriate time".
A spokesperson said: "The benefit cap ensures fairness for hard-working taxpaying households and a strong work incentive, while also providing a much-needed safety net of support."