Fatuma Kadir, from Bolton, left home without her parents’ knowledge on Thursday evening before travelling on several trains to get to London Euston at 1.13am on Friday.
Detectives say the youngster may have travelled to the capital to pursue her dream of owning a clothing business near Tower Bridge.
The last CCTV images of Fatuma show her leaving Euston station on her own, but several public sightings near London Bridge Tube station have led police to believe she may still be in the area.
Her parents, Asheem and Misra, were said to be “extremely worried”.
They said in a statement: “We miss you, we want you to come home. We want to at least know you’re safe. You’re not in any trouble. Please contact us or the police.
“If anyone knows where she is or have seen her, please get in touch with the police.
“We are in a state of shock. We want to know where she is, who she’s with, but most of all, that she’s safe. Fatuma, please come home.”
During a press conference on Friday evening, Detective Chief Inspector Paul Rollinson, of Greater Manchester Police said: “What we know is that Fatuma has got aspirations of setting up a business by London Tower Bridge. However, she might also be intending to do some sightseeing.
“However, this was unplanned. She hasn’t mentioned it to friends or family that she had any intention to travel. We’ve spoken to her two best friends and she gave them no indication that she had planned to go anywhere.”
Police want to trace a man and woman who they believe were worried about Fatuma and travelled on the same train as her from Bolton to Manchester Piccadilly and then to Birmingham New Street.
Police believe the pair may know where she was going after arriving in London.
Fatuma, who was alone when she arrived in London, is said to have a mobile phone with her which is currently not working.
Mr Rollinson said: “We are not aware of any friends or family here but she does have access to some cash. She may have some money to find some accommodation. She may also be travelling back.”
Fatuma is described as an Asian female, of slim build and was last seen wearing a black headscarf and black dress.
The force has said it is “extremely concerned” about her welfare.
Mr Rollinson added: “We’ve been working throughout the night with colleagues from British Transport Police (BTP) and Metropolitan Police and are now releasing a CCTV image of the three when they arrived at Manchester Piccadilly train station.
“We want to ensure that the girl is safe and well and would ask for anyone with information – no matter how small it may be – to come forward.”
Anyone with information is asked to call 0161 856 5757 quoting log number 3275 of 22/07/2021, or report it online at www.gmp.police.uk. Alternatively, you can contact Crimestoppers anonymously on 0800 555111.