Of the 2,007 people polled 27% had seen a hate crime, with 20% witnessing abuse based on religion and 25% on race or ethnicity.
The questionnaire was carried out by Censuswide to coincide with Holocaust Memorial Day on Wednesday.
More than 3,000 events are taking place across the UK to mark the event, which has taken place each year since 2001.
Ceremonies are also being held around the world, including at former death camp Auschwitz, which was liberated 71 years ago.
In separate figures, the Everyday Antisemitism Project - a scheme where Jewish people share experiences of discrimination - reported a surge in submissions, with 303 received in the last three months of 2015, compared to a monthly average of 32 in the preceding 14 months.
Olivia Marks-Woldman, chief executive of the Holocaust Memorial Day Trust, which commissioned the questionnaire, said: "The theme for the thousands of Holocaust Memorial Day events taking place across the country today is 'Don't stand by', and these figures show just how important that message is.
"Today is about remembering the atrocities of the Holocaust and subsequent genocides, but it's also about finding ways to make sure they can never happen again.
"We know that silence and indifference in the face of discrimination and hatred allows persecution to take root, so we want to encourage people to stand up and speak out, in the way many brave souls have in the past."
The most common form of hate crime reported was verbal abuse.
Of the incidents witnessed 28% were online on platforms such as Facebook and Twitter.
More than three quarters of those asked [77%] said there was no difference between bullying or "trolling" someone online and shouting abuse at them in the street.
Some 300 people polled said they had been victim of a hate crime, with 61% saying no-one intervened while the incident was happening.
Censuswide surveyed the over-16s in Britain between 2 and 7 December last year.
Holocaust Memorial Day also remembers atrocities in countries such as Cambodia, Bosnia and Rwanda.
The main UK memorial ceremony will take place at the Guildhall in London and will be broadcast on BBC Two at 19:00 GMT.

They told the BBC they went to the embassy as there was no security for them in the capital city Bujumbura.
Social media has been blocked, radio stations closed and protests banned.
People have been protesting since Sunday over President Pierre Nkurunziza's decision to stand for re-election in June.
African news at it happens: 1 May 2015
The government closed the university on Thursday citing "insecurity".
Earlier on Thursday several hundred students tried to organise a march into the centre of Bujumbura. They wanted to stop the president from officially presenting his nomination papers to the electoral commission.
The students told the BBC's Maud Jullien that the US embassy was the only place they felt safe and that they feared security forces were pursuing them.
She estimates around 500 students are outside the embassy.
The US has not reacted to their presence.
Senior US diplomat Tom Malinowski met Mr Nkurunziza on Thursday, and afterwards said he had warned that the situation in Burundi was "dangerous".
"Some of the measures that have been taken... to shut down social  media, to suspend radio stations not only are wrong as a matter of principle  but very counter-productive," he told journalists.
Rupert Colville from the UN human rights office also said on Friday that he was "deeply concerned" about the authorities' curtailing people's freedom of speech.
At least seven people have died amid the biggest protests Burundi has seen since the civil war ended in 2005.
In a Labour Day radio broadcast Mr Nkurunziza, a former rebel leader, warned of "severe sanctions" against protesters who are found to be behind an "insurrectional movement".
President Nkurunziza said there would be a judicial inquiry into the protests.
Under the constitution, presidents can only be elected to two terms in office but Mr Nkurunziza's allies say his first term does not count as he was appointed by parliament.
Burundi's senate has announced that the constitutional court will examine the legality of the bid.
Mr Nkurunziza has been in power since 2005, when a 12-year civil war officially ended.
More than 300,000 people died in the conflict between the minority Tutsi-dominated army and mainly Hutu rebel groups, such as Mr Nkurunziza's CNDD-FDD.
More than a quarter of people in the UK have witnessed a hate crime in the last year, a new poll suggests.
[NEXT_CONCEPT]
Hundreds of students in Burundi have spent the night in front of the US embassy after their university was closed amid anti-government protests.