A variety of locations are being used to gather tents, blankets, food and clothing due to be sent to Calais.
Over 400 people have pledged to help in Wrexham with groups collecting items in Newport, Cardiff and elsewhere.
Organisers at The Lansdowne pub in Canton said they wanted to help after watching news reports.
In Wrexham, Katie Wilkinson, 27, and friends set up a Facebook group, Wrexham to Calais Solidarity, calling for donated items.
Three collection centres have been set up in the county borough due to the "overwhelming and inspiring" support.
She said: "As the response has been so huge, we are now planning to go directly to the camp in Calais on the 19 September to join others from across the UK and Europe in a day of solidarity."
Ariana Faris, a psychotherapist from Cardiff, is flying out to the Greek island Lesbos on Saturday with her sister, a midwife, to help refugees and migrants there.
Explaining why they have decided to go, she said: "It was the thought that people on the island themselves are just gathering and offering what they can and that we too can do something."
David Cameron has announced the UK is to provide resettlement to "thousands" more Syrian refugees.
Collection centres are being set up in Wales for donated items to help the thousands of migrants caught up in the crisis across Europe.