More than 120 people attended a planning meeting at the Finsbury Park Mosque in north London for the Stand Up to Racism and Fascism protest.
People have begun to organise for the protests in London, Glasgow and Cardiff on 22 March.
Mohammad Kozbar is chair of Finsbury Park Mosque and vice president of the Muslim Association of Britain.
He told Socialist Worker, “Racism and faith hatred are not restricted to any one community.
“We got together with Unite Against Fascism (UAF) to bring all our communities together to fight such hatred. Councillors such as Claudia Webbe and our MP Jeremy Corbyn came.
“We need to stop racists and not allow them to get elected.”
Backers for the Welsh protest include 12 trade unions, the Welsh TUC, the Muslim Council of Wales and the Islamic Council for Wales. Plaid Cymru leader Leanne Wood is among many politicians already backing it.
UAF initiated 22 March as part of a Europe-wide day action called by Greek anti-fascist organisation Keerfa.
In Britain it offers a chance to work with migrant groups and others who oppose the scapegoating of immigrants.
In Chesterfield leaflets for the demonstration have already been translated into Polish.