Home Office figures show a black person living in the Thames Valley police area is 3.5 times more likely to be arrested. than a white person.
And they are more than also significantly more likely to be stopped and searched, data has revealed.
Civil lobbying charity Liberty, which campaigns for justice and equality, has this week accused the police of acting unjustly towards ethnic minorities and called on the government to reduce police powers.
Home Office figures show 2,766 arrests of black people were made in Thames Valley in 2020-21.
This equated to an estimated 40.1 arrests per 1,000 black people in the area, based on population figures from the 2011 census.
In contrast, there were just 11.4 arrests per 1,000 white people.
Arrest rates were down from 2019-20 – before the coronavirus pandemic led to a fall in overall crime – when 42.1 arrests per 1,000 black people and 11.9 per 1,000 white people were made.
Across England and Wales, black people are 3.3 times more likely to be arrested than white people in 2020-21.
Emmanuelle Andrews, policy and campaigns manager at Liberty, said the figures "highlight the injustices that black communities face across the criminal justice system".
Ms Andrews said: "The police should not be handed more powers, and their existing ones must be rolled back."
But the Home Office says "more is being done in policing than ever before to ensure everyone is treated fairly and without prejudice".
A spokesperson added: "We now have the most diverse police force in history and have extensive safeguards in place to hold the police accountable."
Dorset Police had the largest disparity in arrest rates, with black people nearly 11 times more likely to be arrested, while North Yorkshire had the lowest – though a black person was still twice as likely to be arrested.
Habib Kadiri, research and policy manager at StopWatch, an anti stop and search charity, said the racial disparity in arrests is "symptomatic of an attitude that excuses the disproportionate targeting of black people under the guise that they are more likely to be involved in violence and drug crime".
Mr Kadiri also raised concerns regarding racial disparity in stop and search rates.
"The persistent racial disparity in stop and searches demonstrates the degree to which the misuse of frontline policing powers is institutionalised," he added.
Separate Home Office figures show there were 52.6 stop and searches for every 1,000 black people across England and Wales in 2020-21.
This is compared to just 7.5 per 1,000 white people, meaning a black person is more than seven times more likely to be stopped.
In Thames Valley, 20.9 stop and searches per 1,000 black people were carried out, compared to 5.0 per 1,000 white people.
A Home Office spokesperson said: "Every knife taken off our streets is a potential life saved, with 16,000 dangerous weapons removed from the streets and almost 81,000 arrests made last year because of stop and search.
"No one should be stopped because of their race, but tragically data shows that young black men are disproportionately more likely to be the victims of knife crime."