The striker's ex club, Sporting Lisbon has agreed on a £63M with £10M add-ons.
Sporting Lisbon director Andrea Berta: "Viktor has so many qualities.
"He is a quick and powerful presence up front, with incredible goalscoring numbers at club and international levels.
"He brings a clinical edge with a high conversion rate of chances into goals, with his intelligent movement in the box making him a constant threat.
"We welcome Viktor and his family to Arsenal."
He has signed his 5 years deal and done with his medicals at Arsenal FC with his number 14 jersey.
Watch Viktor Gyökeres on his way to the National Stadium ahead of his Arsenal unveiling. ⚽