The man, who was dressed in a grey tracksuit, was assisted by an interpreter during the hearing before being remanded in custody ahead of an appearance at the Old Bailey on Tuesday.
He has also been charged with possessing an offensive weapon.
Police were called shortly before 8pm on Thursday to reports of a man stabbed in the busy central London area, close to the junction with Regent Street.
The Met Police said on Saturday that Mr Dempsey’s next of kin had been informed about the incident and were being supported by specially trained officers.
A post-mortem examination will take place in due course.
The force has asked anyone who can help with the investigation to call police on 101 quoting CAD 7129/01Jul, or to contact Crimestoppers anonymously on 0800 555 111.