The 18-year-old endured a difficult start to life with the Rossoneri following his £1.7m move from Caen, as incidents off the pitch tested the patience of the San Siro hierarchy.
The French youngster was caught driving without a licence, and was also punished by the French FA for frequenting a nightclub on the eve of the Under-20s European Championship playoff loss to Norway.
Reports surfaced in November suggesting that Milan were already planning to offload Niang during the January transfer window, but a dressing down from vice-president Adriano Galliani helped him to reassess his priorities.
"In France, the mentality is different to in Italy, as here you need more professional behaviour," Niang told Corriere della Sera. "I am asked to focus only on football and to be more careful in every aspect of my life.
"In Italy, they are very strict on diet, which is fundamental to avoid injuries. Galliani got angry with me after some incidents and he made me understand I had to change.
"Milan is my big chance and I cannot waste it all because of nightclubs, cars and other distractions. I need to make the most of this opportunity to become an important player for Milan."
Niang has now made eight appearances for Milan.