Nashala Tallah Hearn was suspended from school for five days when she refused to remove her hijab.
The Muslim teenager was told by teachers that it was against the school policy to allow anyone to cover their head in the classroom. One teacher referred to her hijab as a "bandana".
The case is the first of its kind in the US, involving a state school pupil.
After a high profile camapign by civil rights groups and Nashala's family, the Muskogee school district council in Oklahoma, reversed their decision and Nashala returned to the classroom.
A future meeting on uniform and dress code policy is pending.
The teenager told Aljazeera.net that she was relieved to be back at school.
''It made me feel very unhappy when I was told that I wasn't allowed to go to school, but now that I'm back I am smilling and want to get on with learning,'' said Nashala.
'' I feel good that I wear the hijab and I feel proud of being a Muslim ... so when I was told that I had to take the hijab off I refused.''
Muslim women wear hijabs for
reasons of faith and modesty
According to Rose Hearn, Nashala's mother, her daughter was singled out by the school for breaking uniform rules after 11 September.
Rose described to Aljazeera.net how she was telephoned by teachers and told to collect her daughter from the Benjamin Franklin Science Academy.
''I was shocked, I couldn't believe that the teaher had asked Nashala to leave for refusing to remove her hijab. The school knew that Nashala was a Muslim and there was no problem with her wearing the hijab until after the events of 11 September.''
Rose contacted leading Muslim civil liberty groups in the US to ask them for their advice on how to get her daugher back to school and decided to fight for her daughters' right to wear hijab.
''I always thought that America was about freedom of choice, I have lived here my whole life and felt very hurt inside that my daughter was being treated this way because she is a Muslim.''
The school's decision to reinstate Nashala, and to review its dress code has been welcomed by civil rights campaigners.
Ibrahim Hooper, spokesperson for The Council on American Islamic Relations (CAIR) told AlJazeera.net: ''We are delighted for Nashala that she can return to her education, and we would like the school policy of not allowing students to wear head gear revoked.
Teacher Fereshta Ludin who
insisted on wearing a headscarf
"The school has come to a sensible decision to allow her back.''
This high profile case once again puts the issue of Islamaphobia in the US under the spotlight. Post 11 September muslims have been singled out for profiling by law enforcement agencies and have felt vunerable to attack.
Earlier this month, the US House of Representatives passed a resolution condeming violence and bigotry against American Muslims, Arabs and South Asians.