The GMB union has voted to expel any member who participates in racist activities or encourages racist organisations.
They also voted to create a new role of race officer in each branch in order to encourage the diversification and representation of each branch.
Changes to the rule book target anyone "who gives encouragement to, or participates in, the activities of any organisation, faction or grouping whose policies or aims have expressed or implied promotion of racial supremacy or racial hatred at their core".
Kevin Curran, GMB general secretary, said: "Racism and racist activities have no place in our union. We fight institutional racism in workplaces on behalf of our members everyday and it would be nothing less than hypocritical if we were to allow these activities in our own organisation."
"Racism is a cancer in our communities. We want to make it very clear that it has no place in the GMB. Our actions today will ensure we remain an organisation that campaigns against racism and racist activities and upholds our objective of equality for all at work and at home," he said.