The protest was organised outside the Nigeria High Commission by Christian campaigners, exactly one year since Leah Sharibu's disappearance in the north-eastern town of Dapchi.
Chief executive of Christian Solidarity Worldwide (CSW), Mervyn Thomas said: "Leah Sharibu has now been in the hands of [a] violent sect for 365 days and we are deeply concerned by the lack of government action to secure her release."
The 15-year-old was among 110 schoolgirls abducted from their classrooms on 19th February 2018. Leah was the only Christian among the group.
Leah's classmates were subsequently released, following negotiations involving the Nigerian government.
But the teenager remained in captivity for refusing to renounce her Christian faith - an explicit precondition of her release.
Mervyn Thomas from CSW added: "We continue to call on the government of Nigeria to do everything in its power to expedite the release of this courageous schoolgirl..."
Leah is being held by Islamic State West Africa Province - a faction of the jihadist group Boko Haram which is aligned with Islamic State.
The extremists have been waging an insurgency against the Nigerian government in the north of the country since 2009.
Mr Thomas added: "We also call on the government of Nigeria to ensure that the army is sufficiently equipped to combat Boko Haram effectively, particularly in light of the surge in activity by both factions, and their threat to undermine the electoral process."
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