Couzens kidnapped Ms Everard in a rental car as she was driving home alone from a friend’s house in Clapham, south London, in March.
The 48-year-old gun-trained parliamentary and diplomatic protection officer, who had completed his 12-hour shift that morning, raped and strangled the 33-year-old.
Last month Couzens, of Deal in Kent, accepted responsibility for the murder of Ms Everard and pleaded guilty to her kidnapping and rape.
Today he pleaded guilty to his murder when he appeared at the Old Bailey via video link from Belmarsh High Security Prison.
After his arrest, he concocted an elaborate story, claiming he ran into financial hardship after getting into trouble with a gang of East Europeans who threatened him and his family, and asked him to to deliver “another girl” after having underpaid a prostitute a few weeks before.
He told officers that after the kidnapping he handed Ms Everard, still alive and unharmed, to three Eastern European men in a van at a rest area in Kent.
The defendant made no comment in a formal interview and was charged on March 12.
Ms Everard’s disappearance sparked a major investigation, with her body found in a forest in Ashford, Kent, a week later.
She was last seen leaving a friend’s house on Leathwaite Road in Clapham, south-west London, around 9 p.m. on March 3.
The marketing manager chatted with her boyfriend Josh Lowth on her cell phone for about 15 minutes as she set out on foot for the two-and-a-half-mile journey home to Brixton, south London from the London area. Clapham Junction.
That call ended at 9:28 p.m. and footage from a doorbell camera showed her alone.
Just three minutes later, a bus camera appeared to capture the moment she was approached by Couzens in Balham, south London.
Two figures could be seen standing near the rental car, which was parked on the sidewalk with its hazard lights flashing.
After snatching Ms Everard, Couzens left London to arrive in the Tilmanstone area, near Deal, at 1 a.m.
Couzens had booked a rental of a Vauxhall Astra – using his personal details and bank card – on the afternoon of the kidnapping, and had purchased a roll of self-adhesive films a few days before the murder.
Investigators tracked the car’s route using CCTV cameras and ANPR and identified the driver as an agent on duty through the car rental company.
In the days that followed, Couzens reported he was suffering from stress and no longer wanted to carry a gun, according to a case summary.
On March 8, the day he entered service, he declared himself ill.
The next day, police arrested Couzens at 7:50 p.m. – 39 minutes after erasing data from his cell phone.