Ghana midfielder Sulley Muntari will be working under Clarence Seedorf who has been appointed AC Milan coach.
The former Dutch international takes over from Massimiliano Allegri who was relieved off his duty earlier in the week.
Milan have struggled to find the form that made them a formidable force both in Europe and Italy in recent times and will be looking up to a former son in Seedorf to restore the glory days.
"I am here to announce that I will retire from playing after 22 years," the 37-year-old, who has been playing for Botafogo since 2012, told reporters in Brazil.
"It has been a difficult decision, but I am satisfied with what I have achieved in my career. Here at Botafogo I am happy because I leave a team who have qualified for the [Copa] Libertadores.
"I leave an improved club, especially in terms of their mentality and team spirit. Unfortunately, life as a footballer isn't eternal.
"Milan? We will meet again. This experience of the last year and a half has made me grow up a lot and will help me in my next step, as coach of Milan, who have hired me in both an elegant and correct manner.
"I like challenges and coaching Milan will be another challenge in my career. I couldn't say no to Milan after having spent 10 years there.
"The sacking of Allegri was crucial to my decision. The call from [Adriano] Galliani only came yesterday. I want to travel to Milan today. If I don't make it, then I will travel tomorrow.
"I made the decision to join Milan today but last night was a difficult night for me. But I made the right choice. I'm very happy about the opportunity Milan have given me and I'm very motivated.
"I hope that Brazil can have a memorable World Cup and the national team can honour its colours. Thank you."
Seedorf spend 10 solid years will Milan as a player during which he won two champions league and two Serie A titles amongst others.