8 January 2019 10:45 am
Thai immigration officials had tried to return Rahaf Mohammed al-Qunun, 18, to Kuwait, where her family is.
But she refused to board a flight on Monday and barricaded herself into her airport hotel room.
She said she feared her family would kill her as she had renounced Islam.
"My brothers and family and the Saudi embassy will be waiting for me in Kuwait," Ms Mohammed al-Qunun told Reuters.
"My life is in danger. My family threatens to kill me for the most trivial things."
Her relatives have not commented on her claims.
Rights groups including Human Rights Watch have expressed grave concerns for Ms Mohammed al-Qunun, who had travelled to Thailand for a connecting flight to Australia, where she hoped to seek asylum.
The Thai authorities said her status would be assessed by the UN refugee agency (UNHCR).
The Australian government said it would closely monitor the case, calling Ms Mohammed al-Qunun's allegations "deeply concerning".
On Monday evening local time, Thailand's chief of immigration police Surachate Hakparn confirmed that Ms Mohammed al-Qunun was "allowed to stay", and that she "left the airport with the UNHCR".
He earlier said the country would "take care of her as best we can", adding: "She is now under the sovereignty of Thailand; no-one and no embassy can force her to go anywhere.
"Thailand is a land of smiles. We will not send anyone to die."
Mr Surachate said he would meet Saudi diplomats on Tuesday to clarify Thailand's decision.
Ms Mohammed al-Qunun tweeted that her father had arrived, "which worried and scared me a lot", but said she felt safe "under UNHCR protection with the agreement of Thailand authorities".(BBC)