The pair have been friends since playing for Brazil U15s.
"I came first to Chelsea," Andrey, who agreed his deal from Vasco da Gama in January 2023, told chelseafc.com.
"Then, when I saw Angelo was coming too, I was really happy. We have played together since we were 15 years old, we have a connection and a strong bond and so I was happy and looking forward to being able to play with him here at Chelsea. I’m thrilled it’s happened."
Angelo joined Chelsea from Santos and also said: "After a few games at Santos, I became aware Chelsea were interested and then Andrey and I spoke about the club, what it was like, the structure and I was happy and liked the sound of it.
"So, I accepted the offer because it’s a big club, a club of your dreams, a club that plays in the best league in the world, a club with massive history."
Angelo added: "And then, of course, Thiago being here, we aspire to be like him.
"He is an idol to us and our country. He is a reference point. It was also a dream to be able to play with him, learn from him. Setting aside the club’s history and greatness, we are happy to be at this club that has offered us all the support we need to do what we love, which is play football."