The Metropolitan police said 25-year-old Tedi Fanta Hagos from Ravenhill, Swansea, SA5, was charged with murder and possession of an offensive weapon on Friday.
He is due to appear in custody at Westminster Magistrates’ Court on July 3.
The knife attack victim was an unidentified 60-year-old who died in hospital shortly after he was taken to hospital.
The Met said that a post-mortem examination will be scheduled in due course.
It has previously said that the incident was being treated as a random and unprovoked assault and is not terror-related, and that officers were not actively looking for anyone else.
Hagos was subdued by members of the public before police officers arrived.
A witness has told the PA news agency on Thursday that he saw members of the public grab the suspect and disarm him.
The passerby, who asked not to be named, said members of the public “detained him and put the knife in a cylinder.”
“One man grabbed him and soon after the police were there holding him down and he was shouting. I couldn’t hear what he was saying though,” the witness said.
“It was awful. I didn’t see much. Obviously, it’s very busy and I only realised something bad happened when people were shouting and very soon after the police were there.”
Detective Chief Inspector Vicky Tunstall from the Specialist Crime Command said on Thursday that the Met would like to speak to the members of the public who intervened, particularly “two young males with skateboards who led this intervention.”
The Met on Saturday released a image of the skateboarders, one of who used his skateboard to subdue Hagos after the attack.
The Met said the duo didn’t stay to speak with police officers, and that their details are unknown.
“Their key role has only come to light following a review of CCTV and other video footage of the incident and its aftermath,” the Met said in a statement.
Tunstall praised the two men on Saturday and asked the pair to come forward.
“In addition to being immensely brave, we believe these two individuals may also be key witnesses,” Tunstall said.
“In stepping forward as they did to apprehend a violent individual, they showed great courage and potentially prevented others from being attacked,” he said.
“I want to be clear that while they used force to subdue the attacker, those actions were entirely reasonable and are not in question. They can be assured that we wish to speak to them solely as witnesses.”
Tunstall has previously asked witnesses, and anyone who has mobile phone or dashcam footage of the incident to come forward.
PA contributed to this report.