A woman in her 30s, believed to be the partner of father-of-two Couzens, was arrested at the same Kent address on suspicion of assisting an offender.
Human remains found in Kent this week were identified as those of Ms Everard on Friday.
The Crown Prosecution Service has since confirmed Couzens, who was not on duty at the time of Ms Everard’s disappearance, will be charged with her murder and kidnap. He is due to appear at Westminster Magistrates’ Court on Saturday.
In a statement, Rosemary Ainslie, head of special crime at the CPS, said: ‘Following a referral of evidence by the Metropolitan Police related to the death of Sarah Everard, the CPS has authorised the police to charge Wayne Couzens with murder and kidnapping.’
It is understood Couzens worked a 2pm to 8pm relief shift on Wednesday at the US Embassy in Nine Elms, south-west London.
On the night of her disappearance, Ms Everard is thought to have walked from her friend’s in Clapham through Clapham Common towards her home in Brixton – a journey which should have taken around 50 minutes.
She was seen on footage from a doorbell camera walking along the A205 Poynders Road towards Tulse Hill, south of Brixton, at around 9.30pm. Police later searched the Poynders Court block of flats.
Ms Everard’s family and friends described her as ‘beautiful’ and ‘incredibly kind’ as they came to terms with the tragic news that remains had been found amid the search.
A relative of her boyfriend Josh Lowth, 33, described Ms Everard as ‘lovely’ and said the couple had been ‘very happy together’.
University friend Rose Woollard said Ms Everard had only recently told her how ‘excited’ she was to start her new role as a senior marketing account manager.
Describing her as ‘beautiful, thoughtful and incredibly kind’, Ms Woollard, a teacher, told the BBC: ‘She has always been an exceptional friend, dropping everything to be there to support her friends whenever they need her.’
Father Jeremy, a professor of electronics at the University of York, and charity worker mother Sue are believed to have travelled to London from their home in York to help find their daughter.
Couzens’ arrest sent ‘shock waves’ through the Met Police this week, as detectives scoured numerous locations in Kent to find Ms Everard.
His family home where he lives with his wife and two children, in Deal, Kent, was searched by detectives on Wednesday, with witnesses reporting seeing his garden dug up.
Multiple cars were taken away before a metal fence was put up around the property.
Scotland Yard confirmed on Friday afternoon that human remains found in an area of woodland in Ashford, Kent, two days earlier had been identified as Ms Everard.
Metropolitan Police Assistant Commissioner Nick Ephgrave said: ‘Clearly Sarah’s family have been updated with this most distressing news.
‘I just want to pause for a moment and say that my thoughts and prayers, and those of the entire organisation, remain with her and with them at this awful time.’
Scotland Yard is facing an investigation by the police watchdog into its handling of separate allegations of indecent exposure against Couzens.
He was alleged to have twice exposed himself at a south London fast food restaurant three days before Ms Everard went missing.
The Independent Office for Police Conduct is to probe whether two officers ‘responded appropriately’ in their investigation.