Isabel Gayther has not been seen since 11.30am on Saturday, Christmas Eve.
The 21-year-old lives in halls of residence in New Cross, south east London.
The Metropolitan Police said her disappearance is “extremely out of character” and her family are extremely concerned for her safety and wellbeing.
Isabel is known to frequent places popular with students in the New Cross and Deptford areas and has family in Oxford.
She is described as white, with olive skin and long dark hair, is of a slim build. She was last seen wearing a dark-coloured dress.
Police said it is believed she has her phone with her, but that it is unreachable and it is not known if she has access to money or transport.
Anyone who has seen Miss Gayther or who knows of her whereabouts should call police on 101.