Stormzy has said the UK is "definitely, 100%" racist, and that the situation has worsened since Boris Johnson became Prime Minister.
The grime rapper, 26, who released his second album Heavy Is The Head earlier this month, made the comments in an interview with the Italian newspaper La Repubblica.
Asked whether the UK was still a racist country, he said: "Definitely, 100%. It's like: 'Oh no, we're not racist'. But there's a lot of racism in the country.
"The difficult thing with the UK is, as you said, in Italy it's a clear problem, whereas trying to explain that Britain is a racist country is the most difficult thing ever.
"They think: 'No, it's not. Stormzy you're successful. Look at London, there's loads of black people'.
"It's a more difficult case to fight."
Stormzy, who backed Labour in the last election, said Mr Johnson was a "figurehead" whose comments encouraged "hate among others" in the UK.
Mr Johnson has been criticised for using racially charged or offensive language, including describing the Queen being greeted in Commonwealth countries by "flag-waving piccaninnies" and then-prime minister Tony Blair being met by "tribal warriors" with "watermelon smiles" while on a trip to the Congo.
Stormzy said: "If the top person can openly say this racist thing – the 'piccaninnies' remarks, 'watermelon smiles', comparing Muslim women to a letter box.
"If that is our figurehead, the top man, the leader we have to follow, and he openly says these things, he encourages hate among others."
Stormzy, real name Michael Omari, said he was unsure whether he would accept an MBE or OBE if he was offered one.
He said it would be difficult to accept the honour "because of the British empire", but that his mother would be proud if he did.
He said: "It's got a very dark history. You know, Britain colonised everywhere. It's something I'd look into and decide in case of."
Stormzy has been a vocal critic of Mr Johnson.
His number one single Vossi Bop takes aim at the Government and Boris Johnson with the lyrics: "Rule number two, don't make the promise / If you can't keep the deal then just be honest / I can never die I'm Chuck Norris/ F*** the Government and f*** Boris."
And earlier this week, he argued with Piers Morgan on Twitter after the Good Morning Britain host took issue with him criticising Mr Johnson to a group of children.
Stormzy was talking to young pupils at his old primary school in Thornton Heath, south London, when he was asked why he was not a fan of the Prime Minister.
He replied that Mr Johnson was "a very very bad man".
Morgan was quick to comment, writing on Twitter: "He shouldn't have done this, and shouldn't have been allowed to do this."