Plans for the day involved a symbolic 'walk-out' of migrants from their places of work and, in addition to a rally at the Clock Tower from 12:00 noon, attended by Green Councillors Phelim Mac Cafferty and Leo Littman, a mass lobby of Parliament was also organised by the London campaign group.
Green Group Convenor, Phélim Mac Cafferty addressed the Brighton rally and the Green Group have expressed concerns that some migrants wishing to show their support for the event may face punitive measures from their employers.
Phélim Mac Cafferty said: "First hand I know all too much about the sorts of ugly prejudice that immigrants to this country face. When I first came to this country twenty years ago I faced xenophobia and racism. I occasionally face direct prejudice and still face indirect prejudice.
"I am one of the four million EU citizens who have made their homes here in the UK and who in the context of Brexit face losing our rights.
"I have lived and worked in this country for more than half of my adult life and like many others after Brexit it really felt that this was no longer a country that wanted me or other foreigners to be here.
"It is a disgrace that EU nationals have been given no assurance about their right to remain in this country.
"We must be clear that this uncertainty is completely unacceptable and we will oppose any attempt to pit worker against worker."
For twenty-four hours, migrants from inside and outside the European Union, and everyone who supports them, were invited to celebrate the contribution that migrants make.
Some choose to do this symbolically, by wearing badges and lanyards, posting selfies or pictures that showed their support, or putting posters in their windows.
There were many ways to participate and 'celebrate' the most appropriate to your situation.
Green Councillor and spokesperson for Neighbourhoods Communities and Equalities,Leo Littman, said:
"Migrants are our co-workers, our neighbours, our friends. The environment post-referendum has become toxic; with a nationwide rise in racism and hate crimes.
"Our Government refuses to reassure those who have come to work here legally that they will respect their right to remain.
"The resulting uncertainty is unacceptable, and we are keen to recognise the contribution of immigration to our diverse city.
"We applaud those enlightened employers who gave their migrant staff members the day off today, to enable them to highlight their important contribution to the UK and the desperate plight they are now in, suffering such uncertainty about their futures in this country.
"By contrast, I understand that Council staff had to use their annual or flexi-time leave to attend.
"It is very disappointing that the Council"s promised awareness event to highlight migrant workers both within the Council and across Brighton and Hove appears far from being realised.
"At a time when the Council has promised to show leadership and support, swift action to support our migrant community is needed more than ever."