Arsenal announced the move of winger Nicolas Pepe from French league Lille on Thursday for a club-record fee of £72 million ($87 million).
The deal beats the £56 million spent on Pierre-Emerick Aubameyang in January 2018.
Arsenal manager Unai Emery said: “Nicolas is a highly rated and talented winger who was wanted by many of the top teams in Europe.
“Signing a top-class winger has been one of our key objectives in this transfer window and I’m delighted he’s joining.
“He will add pace, power and creativity, with the aim of bringing more goals to our team.”
Pepe said in an interview with Arsenal Media: “Being here is very emotional because it has not been easy for me. I have come a long way and struggled a lot and so signing for this great club is a big reward.”