A further 9,100 Wilko employees will be made redundant by early October, administrators have said.
PricewaterhouseCoopers (PwC) failed to reach a deal to save any significant part of the retailer after it collapsed into administration last month.
"It is anticipated that all stores will be closed by early October, resulting in the redundancies of a further 9,100 employees in those stores," PwC said.
It comes after Sky News revealed a rescue deal involving the owner of HMV had collapsed.
PwC previously announced around 1,600 redundancies at Wilko and confirmed that 52 stores would shut this week after it failed to find a buyer for them.
The administrators said in their statement on Monday: "Staff at 124 stores have today been informed that those outlets will close on, or before, Thursday 21 September.
"Timings for the closure of the remaining 222 stores will be announced in due course."
Earlier, Sky News reported 400 branches of the collapsed retailer would close by early October with the "likely" loss of all 12,500 jobs at the chain, according to the GMB union.
GMB boss Gary Smith told Sky News' Politics Hub With Sophy Ridge that Wilko would cost the taxpayer "tens and tens of millions of pounds" - and that a quarter of the Wilko workers won't get redundancy pay.
He added the law prioritises creditors over job protection, which has led to this situation.
Mr Smith claimed that due to the lack of proper consultation and the resulting redundancies "the taxpayer is going to pick up the bill" for costs related to redundancy payments, failure to consult, and potential notice pay, amounting to tens of millions of pounds.
Although other companies are still in the running to take over some of Wilko's shops, GMB said that these were only interested in the property, and any deals would not include workers.
B&M European Value Retail has already agreed to buy 51 Wilko stores which are set to be rebranded. It is unclear if the discount chain will keep on or rehire any of the Wilko staff at the branches.
A retail executive close to the situation said PwC was also seeking to strike an agreement with the owner of Poundland to offload another 100 Wilko outlets.
The 93-year-old chain, which was founded in 1930 in Leicester, collapsed after being hit hard by inflationary pressures, competition from rival retailers and supply chain challenges.
Zelf Hussain, joint administrator at PwC, said: "As with those who have already been given notice of redundancy, we will guide and support those team members impacted over the coming weeks through the redundancy claims process.
"We also continue to collaborate closely with relevant agencies and engage with any potential employers to help facilitate a quick return into new employment for those impacted.
"We continue to work with potential buyers for different parts of the business and are confident of completing transactions in the coming days."
The following stores will close on Tuesday 12 September:
Cardiff Bay Retail Park
Liverpool Edge Lane
The following stores will close on Thursday 14 September:
Queen Street Cardiff
The following stores will close on Tuesday 19 September:
Hessle Road - Hull
The following stores will close on Thursday 21 September:
Parc Trostre Llanelli
Tamworth Retail Park
Wheatley Retail Park