Tonali had been flirting with a move away from the Stadio Mario Rigamonti with Inter Milan said to be his potential destination.
But the Italy international has opted to join Inter Milan’s city rivals AC Milan after the Nerazzurri became reluctant to sign the 20-year-old.
Milan CEO Ivan Gazidis welcomed Tonali to San Siro and insists the Brescia academy graduate is an exciting talent.
“We are delighted to welcome Sandro Tonali to AC Milan,” Football Italia quoted Gazidis.
“He is one of the most promising young talents in international football. Sandro has a love for the Club and an understanding of its values that will add to what we want to build together. Welcome Sandro!”
Technical director Paolo Maldini also welcomed Tonali.
“We are happy to welcome Sandro to the Rossoneri family,” Maldini said.
“We are convinced he can give an important contribution to build a successful future together. He is a midfielder of great prospects who will know how to interpret the values of our club.”
Tonali expressed his delight in joining the Milanese club and insist donning the famous black and red jersey is a dream come through.
“These are strong, wonderful feelings. I am so happy,” he said.
“Playing with the Milan shirt was a dream of mine, I haven’t worn it yet, but that will happen tomorrow.”
“I will sleep tonight and tomorrow will have a great training session."