The woman claims to be a doctor for the Islamic group based in Raqqa, Syria.
In the picture which was used as her profile picture but has since been removed, the medical student can be seen wearing a full burka and white lab coat while holding the head of a middle-aged man.
To the left of the image, two children can be seen standing beside her.
Her name reflects her jihadi convictions, with Mujahidah appearing to be the female version of mujahadid – meaning soldier of God.
Bint translates as ‘child of’, while Usama likely references Osama Bin Laden.
The image appears alongside the message ‘Dream job, a terrorist doc,’ followed by images of smiley faces and love hearts.
According to the Sunday Telegraph, Bint Usama, who has more than 950 followers (as of publishing) on the social media site, has previously tweeted images of dead soldiers and the 9/11 terror attacks, alongside information on how to treat an injured knee and insomnia.
British intelligence services, GCHQ and MI5 are believed to be monitoring the accounts of around 60 female British jihadis who are believed to be in Raqqa in order to put together a picture of their activities.
The Government has previously stated that those who take part in such acts, including beheadings and massacres will be prosecuted for war crimes and terror offenses if they return to the UK.
In other online messages Bint Usama praised Anwar al-Awlaki, an extremist Yemeni preacher who became an Al-Quaeda spokesman and is believed to have inspired hundreds of Western jihadis.
She also praises women to push their husbands into fighting for Islam, and shared images of the execution of U.S. journalist Steven Sotloff, who was beheaded by ISIS earlier this month.
Mujahidah Bint Usama has been linked through her Twitter account to the al-Khanssaa brigade, an all-female group of jihadists who are charged with punishing ‘un-Islamic’ behaviour by women in Raqqa.
This week members of the brigade, which is thought to be led by British extremists, were reported to be acting as madams running brothels filled with captured Yazidi women, according to the UK’s Mirror.
As many as 3,000 women and girls have been taken captive from the Yazidi tribe in Iraq as Isis militants continue their reign of terror across the region.
The think tank MEMRI (the Middle East Media Research Institution) released a report saying that IS had taken many Yazidi women to be sold and used as sex slaves.
The al-Khanssaa brigade is a female-only militia set up by the Islamic State in Raqqa, Syria, with a key figure believed to be Aqsa Mahmood, 20, of Glasgow, who fled to the country last year.
The UK’s dailymail notes that academics at King’s College London have identified three other British females as members of the group – and say there are about 60 UK women who have gone to Syria on jihad.
Most of these women – including privately-educated Mahmood – are aged between 18 and 24, with al-Khanssaa said to be seeking out people engaging in Western culture in Raqqa.
The UK’s ibt’s reports that social media sites are becoming inundated with requests from UK girls hoping to meet Isis warriors, and Isis have explicitly called on women to come and join the caliphate in order for it to expand.
It is believed that US hostages James Foley and Steven Sotloff were both beheaded in the desert near Raqqa – with speculation that the British women in al-Khanssaa could know who killed them.