Solicitors for X Factor entrant Gamu Nhengu and her family are to seek a judicial review of the Home Office order expelling them from the UK.
Gamu, 18, originally from Zimbabwe and now living in Clackmannanshire, was eliminated from the ITV show on Sunday.
Immigration officials confirmed that her mother, Nokuthula Ngazana, had been refused permission to stay in the UK after her visa expired in August.
Earlier, more than 100 supporters gathered outside Gamu's home.
The family's solicitor, Peter Farrell, said he would be seeking a judicial review of the case from the Court of Session in Edinburgh.
The teenager's family has lived in Tillicoultry, Clackmannanshire, for eight years and she attended the town's Alva Academy.
Mr Farrell said he was still awaiting a written ruling from the Home Office, but understands the application to extend the visa was turned down on the grounds that there was an administrative error in the application filled out by Gamu's mother and that she had claimed benefits she was not entitled to.
He said the administrative error was due to Mrs Ngazana giving the wrong bank details, so the fee for the application could not be taken. The application was judged "out of time" as a result. However he said it was lodged in time.
Regarding the benefits claim, Mr Farrell said Mrs Ngazana was advised by the Inland Revenue that she was entitled to claim Child Tax Credit and Working Tax Credit and that it was aware of her immigration status.
Mr Farrell said he could not go through the normal immigration appeal procedure because the application was turned down on administrative grounds.
But he added: "As soon as we have the decision in writing from the Home Office we will ask for a judicial review of that decision."
"And we will show that our client was given permission by the Inland Revenue in the full knowledge of her immigration status."
Mr Farrell added that once the challenge was lodged with the court the family would be safe from removal until the issue was settled.
A statement from the UK Border Agency said: "The applications made by Ms Ngazana and her family were considered in line with the published immigration rules.
"Ms Ngazana's application was refused as it did not meet all of the conditions for approval.
"Her family, who had applied as her dependants, were therefore also refused."
Officials confirmed they must now leave the UK voluntarily or face removal to their native Zimbabwe.
Ms Ngazana said she was not aware of UK Border Agency's decision and refused to comment on her daughter's elimination from the show.
Local MP Gordon Banks said he had spoken to the family, who were "understandably distraught" by the media reports.
The Labour MP for Ochil and South Perthshire said: "I have spoken to the Border Agency today to find out what on earth is going on.
"There is some suggestion that there may be an administrative problem with the application so we need to get this mess cleared up."
Keith Brown MSP, who represents Tillicoultry, said: "I have known Gamu for a number of years and heard her sing many times. She is the kind of hard-working talent we should have in Scotland.
"Her mother has always been described to me as a model and hardworking student who is now serving as a nurse and if there are any problems over the family's status we should work to resolve them not see them sent away.
"UK immigration and the Home Office need to explain why a talented and hardworking family is facing this situation."
One of the people who gathered outside Gamu's home on Wednesday was childminder Lynn Blackshields who said she thought the singer had an "excellent future ahead of her".
The 40-year-old told the BBC: "I think they're a lovely respectable, hard-working family. I think it's an absolute disgrace that they're being sent away."
And Maegan Muirhead, a 16-year-old pupil at Alva Academy, said Gamu was a "fun person" who had given the school a good name because she had a "rare talent".
"She should stay. She's a great citizen and her mum's working," she added.
A spokesman for the Home Office said the decision to axe Gamu from X Factor was the "business" of the television show.
He could not say whether the omission by judge Cheryl Cole had been decided after talks between immigration officials and the programme's bosses.
Show bosses have denied reports that Cole was influenced by fears that Gamu's visa was due to run out.
A spokeswoman for the ITV1 talent show said: "Gamu's visa being processed was not the reason that she didn't make the final 12."
The Home Office said Ms Ngazana does not have a right to appeal and her singer daughter cannot apply separately to remain in this country.
More than 200,000 people have joined a Facebook campaign calling for the return of Gamu to the show.