Three-year-old daughter Lejla sat on her father Brendan’s lap, while son Cuillin, five, snuggled up to his grandmother in the gallery overlooking the chamber of the Commons.
They heard Prime Minister David Cameron praise their mother as “a voice of compassion whose irrepressible spirit and boundless energy lit up the lives of all who knew her”, while Labour leader Jeremy Corbyn said that, with her death, British society had lost “one of our very best”.
MPs wore white roses in memory of Yorkshire-born Cox, and a single white rose was placed on the green leather bench where she usually sat.
Also in the gallery were Cox’s parents Jean and Gordon and her sister Kim, who wiped away a tear and smiled as fellow Yorkshire MP Holly Lynch fondly recalled how her friend had quickly made her name in the Commons as an MP who was not easy to be whipped.
Several MPs wept as speaker John Bercow told them that the House was meeting in “heartbreaking sadness” and “heartfelt solidarity” to pay tribute to the Batley and Spen MP, who was elected only last year.
After the House was adjourned, MPs processed across the road to St Margaret’s — often referred to as the House of Commons’ parish church — for a service of prayer and remembrance in Cox’s memory.
The killing of the 41-year-old mother of two outside the public library in Birstall in her West Yorkshire constituency has prompted an outpouring of public grief and shaken parliament, which was in recess for the upcoming EU referendum.
Bercow said the killing of the Labour MP — “in this manner, of this person, our democratically elected colleague” — was “particularly shocking and repugnant”.
He hailed her as “caring, eloquent, principled and wise (and)... filled with and fuelled by love for humanity — devoted to her family and a relentless campaigner for equality, human rights, and social justice”.
Her death “strikes not only at an individual but at our freedom”, said Bercow.
In total silence, Corbyn told MPs: “We have lost one of our own and our society has lost one of our very best.
“The horrific act that took her from us was an attack on democracy, and our whole country has been shocked and saddened by it.
“But in the days since, the country has also learnt something of the extraordinary humanity and compassion which drove her political activism and beliefs,” he said.
“Today we remember Jo’s compassion and a passion to create a better world and in her honour we recommit ourselves to that task.”
Cameron said he wanted to “pay tribute to a loving, determined, passionate, and progressive politician who epitomised the best of humanity and who proved so often the power of politics to make our world a better place”.
Recalling first meeting the former aid worker in Darfur in 2006, he said she was “a humanitarian to her core — a passionate and brilliant campaigner whose grit and determination to fight for justice saw her time and time again driving issues up the agenda and making people listen and above all act”.
Shortly before MPs gathered, Thomas Mair, aged 52, from Birstall, appeared at the Old Bailey charged with murdering Cox, grievous bodily harm, possession of a firearm with intent to commit an indictable offence, and possession of a knife.
Following the tributes, Cox tweeted: “Thank you to the whole House & staff for your kindness & compassion to our family today & for describing so well the Jo we love #MoreInCommon”.