The Bosnian has penned a four-year deal with the Gunners and will hook up with his new teammates when they return for pre-season training at the start of next month.
Mirror Football has taken a look at what Arsenal fans can expect from their new signing.
Kolasinac is a left back who has been earning rave reviews in the Bundesliga this season.
His versatility will appeal to Arsene Wenger as he can play in several positions across the back.
He also has experience of playing in midfield due to him being deployed as a defensive midfielder in Schalke’s youth sides.
Kolasinac began his career with his hometown club Karlsruher before having a brief spell with Stuttgart and then joined Schalke.
The talented full-back made his debut for Schalke back in 2012 in a 2-0 win over Greutjer Furth.
Kolasinac also has plenty of European experience and made his Champions League debut against Montpellier in December 2012.
After playing his youth career for Germany, he switched his allegiances to his parents’ homeland Bosnia and Herzegovina.
Kolasinac made his international debut in the 2-0 defeat against Argentina and can boast a World Cup record – albeit it for the wrong reasons.
He scored an own goal against Argentina after just three minutes which was the fastest in World Cup history.
The 23-year-old still has his best years to come and his arrival will cast doubts over the future of Nacho Monreal and Kieran Gibbs who are currently occupying the left back positions.
Despite Schalke having a disappointing season Kolasinac has been one of the star performers scoring three goals and assisting another five goals in all competitions.