Speaking to ITV News Yashika Bageerathi said she was all alone and did not know what she was going to do without her family and friends.
Speaking to her mother as she boarded she said she was scared about landing in the country she fled in 2011.
Speaking to ITV News Yashika Bageerathi appealed directly to the Immigration Minister and the Home Secretary to remain in the UK.
Air Mauritius, the airline due to deport A-level student Yashika Bhageerathi back to Mauritius, where her family and school say she faces "danger" said they "regretted the situation" but had to comply with UK authorities.
Air Mauritius had been contacted by UK authorities during the last weekend, for the repatriation of Miss Bhageerathi.
Considering that all conditions (administrative and security) had not been met, Air Mauritius was not in a position to take the passenger on-board.
Yesterday 1st of April, Air Mauritius received a directive from UK authorities for the repatriation of Miss Bhageerathi.
All conditions having been satisfied, the company had no other choice than to abide by the directive.
The company has taken all steps to ensure that the flight of Miss Bhageerathi takes place in the best possible conditions.
Air Mauritius regrets this situation, but as all airline companies cannot but abide by decisions taken by relevant authorities.
19-year-old Yashika Bageerathi spoke to her mother and her headteacher just as she was getting on to the plane due to deport her to Mauritius.
A last minute injunction to stall the deportation that would have enabled the A-level student to complete her exams failed this evening.
The teenager asked her mother who was going to meet her in Mauritius, and what she should do when she gets off the plane.
Her school and family had urged Air Mauritius to refuse to fly her back to the country where they say she faces danger.
Yashika Bageerathi's school has called on Air Mauritius to refuse to fly her home after an injunction to keep her in the country was rejected.
A spokesman for Oasis Academy Hadley said: "We thought there was a solid legal case for her to stay while she finished her A-levels. It's worrying the legal system doesn't reflect the heart of the people of this country.
"But the plane hasn't taken off yet. This isn't over until it's over. We now ask Air Mauritius not to take Yashika on the plane.
The spokesman pleaded to the airline: "Don't take her from her family to where she faces danger."
The failed last-ditch application to keep Mauritian student Yashika Bageerathi in the country was made as the 19-year-old was being driven to the airport.
She was being taken from Yarl's Wood Immigration Removal Centre in Bedfordshire to Heathrow airport, and is now set to board an Air Mauritius flight at 9pm.
A Home Office spokeswoman said Ms Bageerathi's case "has gone through the proper legal process and our decision has been supported by the courts on five separate occasions".
In such cases, deportation orders are only stayed if a judge decides the case raises issues which are arguable and merit a further hearing.
A judge at London's Law Courts has refused to grant an emergency injunction to block the deportation of Mauritian student Yashika Bageerathi to give her time to take her case to the Court of Appeal.
Yashika Bageerathi's local MP has called on the Home Office to follow their own guidance and allow the 19-year-old Mauritian student to remain in the UK to complete her A-level exams.
David Burrowes said her mother was distraught by what was happening to her, and the Home Office's insistence that she be deported now is unnecessary, as well as uncompassionate.
Lawyers have lodged papers with a judge at London's Law Courts seeking an emergency injunction to block the deportation of Mauritian student Yashika Bageerathi to give her time to take her case to the Court of Appeal.
Shadow Home Secretary Yvette Cooper called on Home Office ministers and officials to apply "a bit of common sense" and use their discretion to decide how and when deportations should take place.
Calling for ministers to stop tonight's planned deportation of 19-year-old Yashika Bageerathi, Ms Cooper said:
Why on earth are UK Border Staff and Ministers insisting that this 19 year old is deported without her family and just months from her A-Levels?
Discretion is there for a reason so they can deal with individual cases in a sensible way. Why not let this teenager get her exams done and have her case handled alongside her family as their own guidance says?
Even at this late stage Ministers should intervene and make sure common sense prevails.
In a letter to the Home Secretary, Labour MP Keith Vaz asked for Yashika's deportation to be delayed and said that to do so before her A-level exams would be "needlessly cruel".
Chair of the Home Affairs Select Committee Keith Vaz has written to Home Secretary Theresa May asking her to urgently reconsider the decision to deport Yashika Bageerathi.
Chair of Home Aff cttee @keithvazmp writes to Home Sec asks her to urgently reconsider decision to deport Yashika Bageerathi. Calls it cruel