They come as Shelter called the situation across England and Wales “utterly awful and unacceptable”.
Every year, the Office for National Statistics collates deaths of homeless people under the age of 75, their location, ages, and cause of death.
The latest estimates from the ONS suggest there was one deaths in Monmouthshire between 2017 and 2021.
There were no deaths in the area last year, with the last death of a homeless person occurring in 2019.
Despite this, across the two countries, the ONS estimates 741 homeless people died in 2021, up 8% from 688 the year before, but down from a peak of 788 in 2019.
The total number of deaths includes people who were identified from death records held by the ONS, together with an estimate of the most likely number of additional registrations not identified as homeless people.
Polly Neate, chief executive of housing charity Shelter, said they are looking at "one of the toughest winters yet" as rents rise while housing benefits stay frozen.
“The Government promised to end rough sleeping, but things are getting worse not better.
"They must immediately unfreeze and increase housing benefit to protect people from the ravages of homelessness this winter, and to keep people off the streets for good it has to invest in building good quality, supported social homes.”
Shelter's comments were echoed by the charity Crisis, which said its services are preparing for “an incredibly challenging winter, with thousands facing the brutality of homelessness as the rising cost of living pushes them to breaking point”.
Chief executive Matt Downie said: "These dire economic times must not lead to more people falling through the cracks and dying needlessly on our streets."
Across Wales, there have been an estimated 142 deaths of homeless people in the past five years.
Due to delays in registrations, around half of the deaths registered in 2021 took place in previous years, the ONS said.
The figures mainly cover people who were sleeping rough or using emergency accommodation such as homeless shelters at or around the time of death.
Across England and Wales, males accounted for 87% of deaths registered in 2021 compared with 13% for females, a ratio similar to previous years.
An estimated 259 deaths were related to drug poisoning, accounting for 35% of the total.
Alcohol-specific causes and suicide accounted for 10% (71 deaths) and 13% (99) respectively.
A spokesperson for the Department for Levelling Up, Housing and Communities said "good progress has been made" toward tackling rough sleeping, but that these figures were a reminder that there is still more to be done.
They added that the Government is providing £2 billion over the next three years to tackle homelessness.