Mrs Cox, 41, died after being shot and stabbed in the street outside her constituency surgery in Birstall, near Leeds, on Thursday.
Eyewitnesses said the mother-of-two was left lying in a pool of blood on the pavement after the incident in West Yorkshire.
Police have confirmed Thomas Mair, of Birstall,was arrested over the killing.
He has since been charged with murder, grievous bodily harm, possession of a firearm with intent to commit an indictable offence and possession of an offensive weapon.
The 52-year-old gave his name as “Death to traitors, freedom for Britain” as he appeared at Westminster Magistrates’ Court in London today.