Amy Pope and Sam Paterson are the first recruits to the Holywell monastic community on an estate in Abergavenny.
Father Mark Soady, vicar of St Mary's Priory Church, will be their prior, leading outreach work in the town.
He said there had been "amazement" that young people were prepared to give up their lives to carry out good works.
The two recruits will initially spend a year living in a house on the estate being supported by the church while they take part in daily services and work with local people.
By day they will arrange activities such as bingo for pensioners, and by night they will take to the streets to talk to young people hanging out in groups.
Father Mark said the inspiration for a modern-day monastic order came from the history of St Mary's, which is on the site of a Benedictine priory which stood from 1087 until 1537 when the monasteries were dissolved.
"When I arrived here two and a half years ago I looked at ways that the Benedictine Rule of Life could pervade the life of the parish on a day-to-day basis," he said.
"My colleagues and I came up with the idea of a new monastic community in the spirit of St Benedict."
Father Mark added: "Abergavenny is a pretty rich town but we have some of the poorest wards in Monmouthshire.
"This juxtaposition of wealth and poverty makes the social divisions more marked.
"We're hoping our work will reduce these divisions."
Unlike the monks of old, the young recruits will not be expected to join the monastic order long-term, but will be given the opportunity to sign up for a second year or seek similar duties elsewhere.
Mr Paterson, 21, is from the Abergavenny area, while Ms Pope, 23, from Watford, Hertfordshire, came to south Wales after answering an advert in the Church Times.
Ms Pope said the role was "a great honour and privilege".
"It's been really exciting so far - Sam and I are just finding our feet," she said.
"We've got involved in a drop-in centre for young people, a parent-and-toddler group and we're hoping to do some work with elderly people.
"I'm hoping that if it all goes well I'll be part of the Holywell community for two years and then go onto ordination training - I'd like to work in mental health."

The gunman fled after opening fire on Annonciate Haberisoni as she was waiting for her hair to be done, witnesses said.
Mr Rwasa accused the government of attempting to assassinate his wife. It has not commented on the allegation.
Tensions have been rising in Burundi ahead of elections in May and June.
Mr Rwasa said at a press conference that his wife was being treated for head injuries at a local hospital, and her condition was not critical.
He would not be intimidated by Sunday's shooting, he added.
Mr Rwasa accused the government of compiling a hit list of people to be targeted in the run-up to parliamentary elections in May and presidential elections in June.
Police said they were investigating the attack.
Witnesses were quoted in the local media as saying that Mrs Haberisoni's life was probably saved by her hair dresser who saw the gunman taking aim and pushed her out of the way.
Mr Rwasa is a former rebel leader and an influential member of the opposition Forces for National Liberation (FNL) party.
He came out of hiding in 2013 and said he would contest this year's election.
President Pierre Nkurunziza has not yet indicated whether he will step down or run for a third term.
He took office in 2005 following the end of a 12-year civil war, which killed more than 300,000 people.
A new breed of modern-day monks is reviving a 1,000-year-old tradition by setting up a Church in Wales "monastery" in a Monmouthshire town.
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The wife of prominent Burundian opposition politician Agathon Rwasa has been shot and wounded at a hair salon in the capital, Bujumbura.