After weeks of talks with Lyon, Lacazette has joined Arsenal for a reported £52million fee which is club record, surpassing the £42.5m fee paid for Mesut Ozil.
The 26-year-old striker will earn £200,000-a-week to also become their highest paid player.
Arsenal said in a statement: “Alexandre Lacazette has agreed to join us on a long-term contract, for an undisclosed fee.
“He is expected to travel with the tour party to Sydney this weekend and is likely to make his home debut in the Emirates Cup on July 29 or July 30.
“The deal is subject to the completion of regulatory processes.”
Manager Arsene Wenger said: “We are very happy to have Alexandre join our group. He has shown over a number of years that he can score goals and that he is a very efficient finisher.
“As well, he has very interesting technical qualities and a strong character. So he is a guy who is a great addition for us, and someone who will help us challenge at the top level this season.”
Lacazette, who had a medical at the training ground yesterday, brings a prolific goalscoring record with 37 goals last season.
He is Arsenal’s second signing of the summer after the arrival of left-back Sead Kolasinac.
Lacazette’s arrival could mean his compatriot Olivier Giroud will leave the Emirates.
Giroud has been linked with a move to Everton in a deal worth around £20million.
The striker has already expressed his loe for the club and what drew him to Arsenal.
“I am of course delighted and very proud too because Arsenal is a legendary club,” said Lacazette. “Throughout my childhood, thanks to Thierry Henry and other French players, I always dreamed of playing for this club so today that dream has been fulfilled.
“Arsenal is also the club which plays the best football in England, so I really wanted to come here.”
“When I play I like to use my pace and to link up with my team-mates. As a forward of course I like to score goals, but that is not all that I’m about.
“I love good flowing football where the whole team is engaged. First of all you need to have players behind you who pass the ball well, resulting in good goalscoring opportunities.”
