Blackwell, 25, suffered a bleed on the brain in a loss to Eubank in March and was put in an induced coma.
The offer comes despite Blackwell saying Eubank and his father were "inhuman" in how they reacted to his life-threatening injuries post-fight.
"I ended the guy's career," Eubank Jr told ITV's Good Morning Britain.
"He said everything was OK and that there were no hard feelings, but I've stopped him being able to make a living.
"I wanted to come and see him because I had something for him, and that something is my British title belt."
READ MORE: 'I could see no light at the end of the tunnel' - Blackwell's trainer
Blackwell woke from his coma a week after the fight, which was stopped in the 10th round, without requiring an operation.
Speaking to the Sun on Monday, Blackwell was critical of the Eubanks' decision to hold a news conference while he was still in hospital.
"I was shocked when I first heard the things he had been saying because we had a little talk on social media," added Eubank Jr.
"I believe that the belt is a goodwill gesture - I'm still ready to come and give it to him.
"The guy's a true warrior, regardless of what's been said, the only thing that's important is that he is now OK, he's with his family and he can live a normal life with no restrictions."
British middleweight champion Chris Eubank Jr has offered to give his title belt to retired opponent Nick Blackwell as a "goodwill gesture".