Milan chief executive Ivan Gazidis wants to sign Arsenal man this summer
Gazidis swapped the Emirates Stadium for San Siro earlier this season and is now planning his first summer of recruitment at his new club.
The Rossoneri are battling for a top-four finish in Serie A as they seek to secure a return to the Champions League.
Gennaro Gattuso's side have the fifth-best defensive record in Italy's top flight this term, but Milan want to further bolster their backline ahead of the 2019/20 campaign.
And Mustafi, who spent two years in Serie A with Sampdoria between , has emerged as a leading target for the seven-time European champions.
The German has endured a difficult season at Arsenal and will be allowed to depart for around £17m.
Unai Emery's side conclude their Premier League campaign with a trip to Burnley on Sunday.