The Holland midfielder made his €55m move in time to be registered by City for the Club World Cup.
“They contacted my father at the end of the season and they were looking for a Number 8, for me it was not a big doubt if I wanted to go to Manchester City, it’s one of the biggest clubs in the world right now,” Reijnders told Sky Sports UK.
“The choice was easy to make. Of course, Milan will always be in my heart, I had two really good seasons there and met very nice people, but you also have to look at the sporting aspect.
“I want to reach some goals in my career and I think that I can reach those here quickly.”
Pep's the best in the world
Reijnders admits the chance to play for Pep Guardiola was also a big attraction.
"That is also a big thing of course, he is the best coach in the world, I am eager to learn new things and a new style of playing. I’m very much looking forward to it.”
He added, “I am a box-to-box player who likes to carry the ball, to be also in the build-up and eventually connect to the attacking part, finding assists and goals. That is what I also want to bring to City.”