Far right fanatic Thomas Mair has been handed a whole life term for murdering the Labour MP in what prosecutors called an "act of terrorism".
Mrs Cox was stabbed 15 times and shot outside her constituency office in Birstall, West Yorkshire.
A taxi driver has described seeing MP Jo Cox being stabbed five or six times by a man who warned onlookers to "better move back".
Rashid Hussain told the jury at the Old Bailey he had dropped off a fare when he was alerted to loud noise like "fireworks going on".
He then described seeing a man "stabbing somebody" behind a car.
"He was standing up and she was on the road...she was bleeding, Mr Hussain said.
"I said: 'what are you doing, what's wrong with you.' He said: 'Move back, otherwise I'm going to stab you.'"
Mr Hussain added: "He said something and the last words were 'Britain first.'"
Thomas Mair, 53, is accused of murdering the 41-year-old outside her constituency surgery in Birstall, near Leeds, on June 16.
Mair is also charged with causing grievous bodily harm with intent to Bernard Carter-Kenny.
He has denied all the charges against him.
She may have only served her constituents for little more than a year, but those whose lives Jo Cox touched won't forget her lasting legacy.
Thomas Mair is being described as an extremist, a fanatic, an assassin – even ‘a constituent’. But make no mistake – he is a terrorist.
Thomas Mair "betrayed the quintessence of our country" in the senseless killing of MP Jo Cox, the judge said.