The Bosnian previously attracted interest from top clubs in the Premier League and across Europe and was the subject of a failed bid from Chelsea in January. The Gunners have beaten the likes of Chelsea, Juventus and Manchester City to sign the highly rated 23-year-old Bosnia and Herzegovina worldwide.
Unlike Arsenal's current crop of full backs, Kolasinac actually is a defender who defends.
The 34-year-old told Spanish radio station Cope: "I didn't say goodbye to (manager Zinedine) Zidane because Zidane and Real Madrid knew I was going before I did".
The left-back completed a medical and agreed personal terms with the club at the end of April.
Kolasinac previously played worldwide football for Germany at underage level, before switching allegiance to Bosnia and Herzegovina, which is his parents' homeland. Till June 30, he remains a Schalke player.More news: Apple 'HomePod' speaker to take on Amazon, Google
"I fought [every] game to play for my club in order to achieve the maximum success [for] Schalke".
"I'm really flexible", Kolasinac added. My strengths of my mentality.
'I think left-back is where I feel most comfortable.
Sead Kolasinac looked pleased to finally be wearing an Arsenal shirt after he was unveiled as the club's first summer signing on Tuesday.
And it's an interesting message indeed, especially the specific emphasis on Arsene Wenger's involvement in helping bring the player to Arsenal instead of one of his other European rivals.