The 21-year-old Germany midfielder joined in a £72million move from Bayer Leverkusen during the summer transfer window - following in the footsteps of his compatriot Werner.
Asked whether it helped that 24-year-old Werner was already at Chelsea, Havertz said: "It helped a lot. We know each other well from the national team.
"We've always been big friends. When I got the news that he would change [clubs] of course we messaged like every day.
"He always said to me, 'Come, come [to Chelsea]!' It was like every day."
Havertz said it was a bonus that there were other German-speaking players already at the club.
"Of course it's easier for me to have some German-speaking players here," Havertz added on Chelsea's YouTube channel.
"We have Timo, Toni Rudiger and Pulisic and Kovacic can also speak German which is good for me.
"But I can speak English as well so I have a good relationship with every player - but of course me and Timo are big friends and it was very important for me that he made the step and I made it too."