The unidentified girl had claimed that high school teacher Samuel Paty showed an image depicting the Prophet Mohammed during a lesson on free speech.
She said that Paty had asked Muslim pupils to leave the class before he showed the image, which had appeared in the satirical magazine Charlie Hebdo.
On Monday, the girl's lawyer revealed that his client, 13, had confirmed that she did not actually attend the class and was off sick at the time.
'She lied because she felt trapped in a spiral because her classmates had asked her to be a spokesperson,' lawyer Mbeko Tabula said.
After the girl, who reportedly had a history of behavioural problems, made her initial claims about the class, her father filed a legal complaint and posted a video online in early October.
The video, which detailed the allegations against Paty, provoked outrage on social media, including death threats against the teacher.
A French schoolgirl has admitted to telling lies about a teacher who was beheaded after an online hate campaign kickstarted by her comments. The unidentified girl had claimed that high school teacher Samuel Paty showed an image depicting the Prophet Mohammed during a lesson on free speech and that Paty had asked Muslim pupils to leave the class before he showed the image, which had appeared in the satirical magazine Charlie Hebdo. Pictured: A memorial to Paty at the city hall in Conflans-Saint-Honorine [File photo]
On Monday, the girl's lawyer revealed that his client, 13, had confirmed that she did not actually attend the class and was off sick at the time. Pictured: People gather in Paris to pay tribute to Paty on October 18 [File photo]
Paty was beheaded in the street by an 18-year-old man of Chechen descent on October 16. The man was shot dead by police shortly after the attack.
The girl has been charged with slander, while her father and an Islamist preacher have been charged with complicity in the killing.
Paty's killing, which happened in the town of Conflans-Sainte-Honorine, sent shockwaves through France and reignited tensions in the country over the strict divide of church and state.
President Emmanuel Macron's response defending the cartoons of Mohammed and Paty's actions sparked mass protests and boycotts of French goods in many Muslim-majority countries.
The Prophet Mohammed is extremely revered in Islam, which prohibits the depiction of animate objects including people and animals.
Visual representations of Mohammed or Allah are considered particularly egregious by some followers of the faith.
The offices of Charlie Hebdo, the magazine which published the cartoons of Mohammed, were the subject of an attack in 2015 in which 12 people were killed.
France has been hit by several major terror attacks in recent years. Its fiercely secular state was founded on the concept of laïcité, which separates state institutions - including schools - from the influence of religion.
French President Emmanuel Macron's response defending the cartoons and Paty's actions sparked mass protests and boycotts of French goods in many Muslim-majority countries. Pictured: An effigy of Macron is burned in Kolkata, India on November 4
Following Macron's comments on Paty's killing, three people were killed in a terrorist attack at a Catholic church in Nice on October 29. Pictured: French police guard the Notre-Dame Basilica in Nice where the killings took place [File photo]
In recent years, this policy has chafed with the reality of France's multicultural population, particularly Muslims, some of whom feel they have been unfairly targeted by secularism policies including a ban on the wearing of some forms of Islamic dress in public spaces.
Teachers are increasingly on the front lines of this contentious and deeply-felt debate.
On Monday, the government warned that a poster campaign by students in Grenoble risked putting two university professors' lives at stake. The posters accuse the academics of Islamophobia.
A proposed law under discussion in the French parliament would make sharing information about a state employee online punishable with prison if it was known posting such information could cause the person harm.
The draft law comes after parliament approved a law aimed at fighting 'Islamist separatism' by banning 'hate preachers' and giving police the power to close religious schools.
On February 16, France's lower house voted in favour of the law billed by the government as a riposte to religious groups attempting to undermine the secular state.
The draft legislation, which has been criticised for stigmatising Muslims and giving the state new powers to limit speech and religious groups, was backed by a clear majority of MPs in the National Assembly.
Macron has been accused of pandering to far-right voters by exaggerating the danger of Islamist groups in the often-marginalised communities found in French suburbs.
The government counters that the threat is real, pointing to repeated terror attacks and what Macron called the development of a 'counter-society' that rejects secularism, equality and other French values and laws.
Macron (pictured) has been accused of pandering to far-right voters by exaggerating the danger of Islamist groups in the often-marginalised communities found in French suburbs [File photo]