Administrators acting for the Wakefield-based company said they hope to sell the rest of the business to the group’s sister chain Peacocks.
The 30 stores, which employ around eight people each, will close down on December 11 and the staff will “potentially be made redundant”.
Around 240 people work at the underperforming stores.
Some 25 others have already lost their jobs in head office and middle management.
Administrator Tony Wright, from FRP Advisory, said: “We deeply regret that, as part of the administration process, 30 stores will close and staff may be made redundant.”
The 285 stores that are left will continue to trade but they will be kept under review and their future cannot be guaranteed.
The administration put a potential 2,887 jobs at risk across the country.
The closures come as part of a deal with sister company Peacocks, which itself entered administration in 2012, along with Bonmarche.
The two were rescued at the time by private equity firm Sun European Partners.
However, administrators stressed that the deal still hinges on negotiations with landlords, and due diligence, and could yet fail.
“Whilst we are optimistic that a transaction can be completed, ultimately it will depend on ongoing negotiations between our preferred bidder and landlords on market rents and there remains a risk that the business could cease to trade,” warned Mr Wright.
Nine companies are understood to have been in the running to take over Bonmarche, but Peacocks was chosen as the preferred bidder after the deadline passed on November 15.
Bonmarche fell into administration in the middle of October after the firm issued a series of profit warnings.
It blamed a “sustained period of challenging trading conditions” as the business became the latest victim of a malaise on the high street.
Bonmarche had been listed on the London Stock Exchange until earlier this year when retail tycoon Philip Day took over the struggling retailer.
The firm has become the latest victim of the high street slump.
The group, which caters for fashion conscious women over 50, previously had 200 at its Wakefield head office and operated 318 stores across the UK.
Mr Wright, Alastair Massey and Phil Pierce of specialist advisory firm FRP were appointed as joint administrators for the firm in October.
Mr Wright said that Bonmarche has been a staple on the UK high street for nearly three decades, but the persistent challenges facing retail have taken their toll and led to the administration.
The firm has recently struggled with rising costs, such as business rates and rising wages, as well as dwindling footfall on UK high streets.
Bonmarche said the high street is going through a period of “historic difficulty” and the firm has been unable to weather the economic headwinds impacting the whole of the retail sector.
Bonmarche is the latest in a long run of retailers to fall into administration.
House of Fraser, Debenhams, Karen Millen and Coast have all gone into administration over the past two years.
Other retailers such as Marks & Spencer have closed stores, often leading to a further slump in high street spending as towns have lost their key M&S store.
Shoppers appear to be holding back on unessential spending until the Brexit fog clears.
On top of this, the slump in the pound has raised the cost of clothing imports.