The research also found that reports of racist remarks, verbal abuse and intimidation had all increased since 2020.
36% of black workers said they witnessed racist verbal or physical abuse, 36% heard racist remarks, and 35% experienced verbal abuse.
The percentage of those whose ability to speak English was questioned rose to 31% from 20%.
Reports of physical violence or threats went up from 19% in 2020 to 26%.
Sharing of racist content on social media increased to 28% from 22%, and racist literature or music in the workplace went up to 25% from 19%.
Black workers were twice as likely as white workers to be questioned about their culture or religion in an offensive way (35% compared to 18%), have their English questioned (31% compared to 16%), or hear racist remarks (36% compared to 19%).
28% of black workers said direct managers were responsible for the last incident of unfair treatment or racism, 22% said colleagues, 16% said other managers and 12% said customers.
Unfair treatment was most often by direct managers (35%), bullying by managers (30%) or colleagues (28%), and explicit racism by colleagues (33%) and customers (22%).
17% of black workers who faced unfair treatment, racism or harassment said they left their job after the most recent incident.
23% wanted to leave but could not.
Data also showed that 23% of black workers said they did nothing after the latest incident, down from 28% in 2020.
30% told a friend or family member and 27% told a colleague.
21% reported the incident to their employer, up from 16% in 2020. 11% raised a grievance, 10% got legal advice, 10% got help from their trade union, 10% went to a community organisation and 9% took an employment tribunal case.
Black union members were more likely to report incidents to their union (18%) than non-members (10%).
Union members were more likely to report incidents to their employer (31% compared to 18%), raise grievances, get community support and go to tribunal.
Of those who reported incidents to their employer, 69% said the issue was taken seriously.
19% said their complaint was not believed, up from 11% in 2020. 63% said things got better after reporting, 15% said things got worse and 20% said nothing changed.
24% said their employer took action to prevent harassment, 24% said disciplinary action was taken, 13% said other action was taken, 15% said there was an informal investigation and 19% said a formal one.
16% were transferred to another department after reporting, up from 5%. 13% were isolated from colleagues, up from 3%, and 7% were disciplined or faced a counter complaint.
60% were satisfied with their employer’s response, 18% were dissatisfied and 21% were neutral.
Common reasons for not reporting included no confidence it would be dealt with (17%), concern it would make things worse (17%) or not thinking the issue would be taken seriously (16%).
73% of black trade union members were satisfied with their union, compared to 64% of white members.
Black workers were more likely to get support from their union on rights at work, pay negotiations and health and safety.