Student Yashika Bageerathi is said to be "very frightened" after landing in Mauritius following her deportation on Wednesday night.
Several last minute efforts were made to prevent the teenager being sent to her native country, including an emergency court order and an appeal from chairman of the Home Affairs Select Committee Keith Vaz.
The 19-year-old was taken on an Air Mauritius flight and is looking for somewhere safe to stay following a police interview at the airport, her headteacher said. Ms Bageerathi had been predicted top grades in her A-levels and had already been offered places at Russell Group universities before she was sent back home.
Friends, family, politicians and her school have all campaigned to prevent her deportation, to no avail.
Ms Bageerathi came to the UK with her mother, sister and brother in 2011 to escape a relative who she said was physically abusive, and claimed asylum last summer.
Lynne Dawes, headteacher at Oasis Academy Hadley in Enfield, north London, said the school was in regular contact with the promising student and that the immediate concern was to find her a safe place to stay.
But Ms Dawes added they were working to ensure she would still be able to complete her A-levels.
She described the student as feeling "low" and said: "She's feeling the lowest I have heard her be for quite a while.
"She was also very subdued."
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The headteacher confirmed four security guards had accompanied Ms Bageerathi on the flight.
A spokesman for the Oasis charity, which runs the academy, said they were supporting the family, as well as the student, who he described as "very frightened".
He added: "Yashika's mum is very upset understandably, she's very emotional and she's very worried.
"Worry is the overriding feeling."
The Rt. Hon. Theresa May MP, Home Secretary: #FightForYashika Stop this sixth form student being deported alone. She deserves a future!— Cara Delevingne (@Caradelevingne) March 23, 2014
Previous attempts to deport Ms Bageerathi were thwarted when Air Mauritius refused to fly her out following an earlier refusal by British Airways - but Air Mauritius confirmed it had received a "directive" from the UK authorities that the youngster must leave.
The deportation followed a judge at London's Law Courts refusing to grant an emergency injunction to block the deportation to give her time to take her case to the Court of Appeal.
The last-ditch application was made yesterday as the youngster was being driven from Yarl's Wood Immigration Removal Centre in Bedfordshire to Heathrow airport.
Even last-minute attempts by Keith Vaz MP to stop the deportation failed after he had written to the Home Secretary to ask her to "urgently reconsider" the decision.
In his letter to Theresa May yesterday, Mr Vaz said: "It is hardship enough for this young woman to be separated from her family and returned to Mauritius, where she claims she fears persecution.
"To interrupt her education at this late stage in order to do so seems needlessly cruel."
Ms Bageerathi, whose case sparked a petition that has attracted around 178,000 signatures, had been detained at Yarl's Wood since March 19.