According to its website, PM Law employed over 600 people at firms, including Proddow Mackay, Butterworths Solicitors, WB Pennine Solicitors and Angela Viney Conveyancing Services.
Several employees reported turning up for work on Monday to discover a notice on the window explaining the business could no longer trade because of “regulatory matters”.
Others noticed something was amiss when they were locked out from internal systems.
One member of staff, who did not wish to be named, said there had been no explanation about what had happened or what employees were expected to do next.
“I’m devastated at the way they’ve treated us,” she told the BBC.
“They’ve not given us the time. Usually in these kind of situations, where a company’s going under, they generally put a plan in place. But there’s nothing at all. It’s just soul destroying.”
The woman, who had worked at the office in Shepcote Lane, Sheffield, for more than a decade, said there had been no indication of what was happening.
“We should have been going on a night out this Friday, the building was supposed to be starting refurbishment,” she said.
“So, it’s not just the staff and clients, [but also] contractors. The domino effect is just massive.”
She urged the company to provide guidance to people and advice on next steps.
“There’s not even been an apology,” she said.
“Lord knows what’s happened. It’s got to be something catastrophic for it to happen overnight.”