Mrs Cox, 41, died after being shot and stabbed in the street outside her constituency surgery in Birstall, near Leeds, on Thursday.
Thomas Mair, 52, from Birstall, appeared at Westminster Magistrates’ Court in London charged with murdering Mrs Cox, grievous bodily harm against a pensioner who tried to help her, possession of a firearm with intent to commit an indictable offence and possession of a knife.
Mair, who was brought to court in a police convoy, refused to give his correct name to the court and remained silent when asked his address and date of birth.
He wore a grey jumper, tracksuit bottoms and black shoes and was handcuffed to a guard in the dock during the hearing.
Mair was not required to enter a plea at court and his lawyer Keith Allen said there was no indication of what plea would be given. He also told the court that legal aid has been applied for.
Deputy Chief Magistrate Emma Arbuthnot ordered that he be remanded in custody until his next appearance, a bail application at the Old Bailey on Monday.
He will be held at Belmarsh Prison, and Ms Arbuthnot suggested that a psychiatric report should be prepared, saying: “Bearing in mind the name he has just given, he ought to be seen by a psychiatrist.”
Mrs Cox was attacked after spending Thursday morning at a local school and a care home when she made her way to a pre-arranged constituency surgery in Birstall library at lunchtime.
At around 12.45pm, after she got out of her vehicle in Market Street, a man approached and began attacking her with a knife.
Bernard Kenny, 77, who was waiting in his car after dropping his wife off to visit the library, went to Mrs Cox’s aid and tried to save her, but was himself stabbed and forced to retreat to a sandwich shop to seek cover.
Mrs Cox was then repeatedly stabbed, shot three times as she lay on the ground, and then stabbed again as she fought for her life.
Mrs Cox died at 1.48pm.