The event, which will be held online because of coronavirus restrictions, aims to mobilise funds and raise awareness of the plight of more than five million people who have escaped the political and economic chaos engulfing Venezuela under President Nicolas Maduro.
"Venezuela's neighbouring countries have shown great generosity in hosting many Venezuelans that have fled their country," Borrell said in a statement.
"Their effort and solidarity should serve as an example to all. We are committed to supporting them at this critical time."
More than 40 countries will take part, the EU said, along with UN agencies and international financial institutions and aid organisations.
Oil-rich Venezuela has suffered economic collapse and political turmoil under hard-left leader Maduro, a situation made worse by the coronavirus pandemic.