Brendan Cox’s message came after a day of tributes and tears in the House of Commons as politicians gathered to pay respects to the popular MP, who died after being shot and stabbed in her Batley and Spen constituency.
Friends of Mrs Cox set up the Go Fund Me page in “celebration and memory” of the popular MP, and it passed the £1 million mark shortly before 8.30pm on Monday after more than 30,500 people made donations that will be divided between three charities.
Mr Cox tweeted: “Thank you to everyone for your incredible generosity. This will change lives in Syria, Batley and across the UK.”
The fund was pushed past the seven-figure mark by a £6,000 donation from a “David Newton” which joined offerings small and large that have poured in over the last three days following the Labour MP’s death after she was attacked outside the library in Birstall, Yorkshire.
Mrs Cox’s friend Tim Dixon, one of those who launched the fund, said: “The scale and speed of the public response to this fund has been overwhelming and deeply gratifying to Jo’s family.
“It shows how powerfully Jo’s story has moved so many. Jo would be so proud.”
Go Fund Me said the appeal was the largest UK campaign it has seen, and the third largest globally.
Earlier, Mr Cox and the couple’s children came to the House of Commons to hear emotional tributes to their mother as Parliament was recalled to pay its respects four days after her death on Thursday.
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.
Prime Minister David Cameron praised Mrs Cox 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”.
Labour’s Rachel Reeves, whose constituency of Leeds West is just a few miles away from Mrs Cox’s, broke down in tears as she remembered her friend of ten years.
MPs wore white roses in memory of Yorkshire-born Mrs Cox, and a single white rose was placed on the green leather bench where she usually sat.
They took the unusual step of rising to give Mrs Cox a standing ovation as the hour-long tribute drew to an end, before a service of prayer and remembrance at nearby St Margaret’s - often referred to as the House of Commons’ parish church.
Earlier, the pensioner who tried to save Mrs Cox was released from hospital as calls grew for him to be officially honoured for his bravery.
Bernard Kenny, 77, was stabbed in the stomach as he came to her aid.