The 24-year-old has joined the Croatian club on a one-year loan deal, with the option to make the transfer permanent in the future.
Bennacer has been with AC Milan since 2016, but has struggled to establish himself as a regular starter in the team.
He made 23 appearances for the Italian club last season, but only started 10 games. He scored one goal and provided four assists during his time with AC Milan.
Despite his limited playing time, Bennacer has been capped 22 times by the Algerian national team and has scored one goal.
Dinamo Zagreb has been bolstering its squad in recent years, and the signing of Bennacer is seen as a significant coup for the Croatian club.
The club's manager, Igor Cvitanovic, has said that Bennacer will bring experience and quality to the team.
Bennacer's arrival is seen as a boost for the team ahead of the upcoming season, and fans are eager to see how he will perform in the Croatian league.
The signing of Bennacer is a signal that Dinamo Zagreb is committed to improving its squad and competing at the highest level.
The club's owners have invested heavily in the team in recent years, and the signing of Bennacer is seen as a key part of their strategy to succeed in the Croatian league and in European competitions.
The 24-year-old midfielder will be looking to make a strong impression in his new team and help Dinamo Zagreb achieve its goals for the upcoming season.