Cox was shot and stabbed to death on the way to meet locals in her constituency last week, a murder that upended campaigning ahead of Thursday’s vote on European Union membership.
Brendan Cox told the BBC that Jo had “died for her views”.
“She was a politician and she had very strong political views and I believe was she killed because of those views,” Brendan said.
“I think she died because of them and she would want to stand up for those in death as much as she did in life.”
Cox worked for Oxfam before becoming a politician and was known for her pro-EU campaigning and advocacy of refugee rights.
On his first appearance in court, the man charged with her murder, Thomas Mair, gave his name as “Death to traitors, freedom for Britain”.
The violence on a village street in Yorkshire in northern England prompted questioning over whether the rhetoric of the campaign had been too divisive.
“She worried about the tone of the debate… the tone of whipping up fears and whipping up hatred potentially,” Brendan said.
“She was definitely worried about that, but it’s not just about the EU referendum, I think the EU referendum has created a more heightened environment for it,” he added.
Brendan Cox ruled out seeking the nomination to stand as a candidate in his wife’s constituency of Batley and Spen, saying his priority was to look after their two children, aged three and five, and to ensure that “something good” comes of their mother’s murder.
Donations to a memorial fund for causes Jo Cox supported, such as The White Helmets search and rescue volunteers in Syria, have reached almost £1.2 million ($1.7 million, 1.6 million euros).
Events are set to be held in cities including London, Brussels and New York in her memory on Wednesday, on what would have been Cox’s 42nd birthday.