The Government's treatment of the Windrush generation has been branded "disgraceful" as the Prime Minister announced plans to create a memorial.
Up to £1 million in funding has been earmarked by the Ministry of Housing, Communities and Local Government for the permanent monument at London's Waterloo Station.
Meanwhile, mayor of London Sadiq Khan hailed the "enormous contribution" made by the Windrush generation as he announced funding to help Londoners access legal support to secure their immigration status.
Mr Khan said the way the Windrush generation and their families have been treated by Government is a "national scandal" as he pledged to invest up to £370,000 to support the immigration advice sector in London.
Both the memorial and the mayor's funding were announced on Saturday, as the first Windrush Day is observed to mark 71 years since the arrival of the first "pioneers".
Situated at the country's busiest railway station, Theresa May said the memorial will be seen by "millions of people from all around the world" every year.
Mr Khan said: "The Windrush generation have made an enormous contribution to our country and to the success of our great city, influencing almost every aspect of our culture and modern life. We owe them an enormous debt of gratitude.
"But the disgraceful way the Windrush generation and their families have been treated by the Government is a national scandal.
"Their experiences clearly demonstrate that the immigration process is difficult to navigate and the increasing severity of the hostile environment is putting Londoners with the right to be here at risk of destitution.
"That's why I'm taking action on Windrush Day to make sure that Londoners are not let down again.
"I am investing in legal advice to support vulnerable Londoners – many of whom may have lived here most of their lives, have been through school here, and worked and paid taxes here.
"The Government has already failed the Windrush generation, but we have to act now to stop an injustice like this from happening again."
On this Windrush Day and every day, let us give thanks to those pioneering men and women. They crossed an ocean to build a future for themselves, their communities and the UK, the country that will always be their home. pic.twitter.com/YvUeEB0U2d
— Theresa May (@theresa_may) June 22, 2019
Mrs May said: "The Windrush generation helped lay the foundations for the country we know today, which is richer and stronger as a result of their hard work and dedication to the UK.
"This monument will be a lasting legacy to the tremendous contribution the Windrush generation and their children have made to our great country."
June 22 was the day when around 500 migrants from the Caribbean arrived at Tilbury Docks in Essex in 1948 aboard the MV Empire Windrush, at the invitation of the British government, to help rebuild the UK in the aftermath of the Second World War.
But in recent years, ministers and the Home Office have come under fire over revelations on how members of the Windrush generation and their children have been wrongly detained and deported – and others denied access to healthcare, work, housing benefits and pensions.
In the wake of the scandal, the Prime Minister established the Windrush Commemoration Committee to consider how best to create a permanent, fitting tribute to the Windrush generation and their descendants.
The committee's chairwoman, Baroness Floella Benjamin, said: "Having a Windrush monument located at Waterloo Station where thousands of Windrush pioneers – including children like myself – first arrived in London, will be a symbolic link to our past as we celebrate our future.
"The Committee is determined to build a monument of great beauty and emotional impact which will lift the hearts of those who visit when it's unveiled. I hope it will inspire pride and a sense of belonging to all those associated with the Windrush story."
The committee will work with designers over the coming months on a scheme for the memorial.
Communities Secretary James Brokenshire said: "Waterloo Station has been the gateway for generations of people coming to Britain. It stands at the heart of the Windrush story and will provide a central location to allow us all to reflect on our shared history and heritage.
"As communities across the country celebrate National Windrush Day, people in years to come will have a permanent reminder of the outstanding contribution of the Windrush Generation and their descendants."