The Brazilian winger was targeted by chants from sections of the crowd during Real Madrid's 1-0 loss to Valencia on Sunday (21.05.23) as the match was stopped for 10 minutes after he grabbed the referee and pointed out the fans who had targeted him.
Vinicius Jr was later shown a red card for an altercation with Valencia striker Hugo Duro.
He tweeted after the game: "It wasn't the first time, nor the second, nor the third. Racism is normal in La Liga. In football they think it's normal, the federation does too - and the opponent encourages it.
"I'm so sad. The championship that once belonged to Ronaldinho, Ronaldo, Cristiano [Ronaldo] and [Lionel] Messi today belongs to racism.
"A beautiful nation, which welcomed me and which I love, but which agreed to export the image of a racist country to the world.
"I'm sorry for the Spaniards who don't agree but today, in Brazil, Spain is known as a country of racists. And unfortunately, for something that happens each week, I have no defence. I let it happen.
"But I am strong and I will go to the end against racists. Even if it is far from here."
Real have lodged a hate crime complaint in response to the abuse and expressed support for Vinicius Jr.
He said: "Real Madrid strongly condemns the events that took place yesterday against our player Vinicius Junior. These events represent a direct attack on the social and democratic model of coexistence of our state based on the rule of law.
"Real Madrid believes that such attacks also constitute a hate crime and has therefore filed the corresponding report with the Attorney General's Office, specifically with the Prosecutor's Office against crimes of hatred and discrimination, in order for the facts to be investigated and for those responsible to be held accountable."