Both sides in the campaign had already put activities on hold when news of the attack on Mrs Cox first emerged and swiftly confirmed that suspension would remain in place following the announcement of her death.
David Cameron cancelled a planned rally in Gibraltar and the BBC scrapped plans for two referendum-themed programmes including a schedule Question Time in York.
Confirming the suspension if its activities, Will Straw, executive director of Britain Stronger In Europe, the official Remain campaign, said: “Jo Cox was a good friend and my thoughts are with her husband, Brendan, and her two small children, Cuillen and Lejla.
“She was a wonderful woman, dedicated campaigner and a hard-working MP. Inside and outside Parliament, Jo had fought for a more peaceful and just world. It is senseless that her life should be cut short in such a brutal manner.
“This tragedy has shocked everyone in the campaign and especially those in Yorkshire who had been working with her.”
A senior Vote Leave spokesoman also confirmed its planned campaigning for today would not go ahead.
The decision was mirrored by the UK Independence Party, which had planned to launch a new advertising campaign.
Several MPs said they would be cancelling their advice surgeries.