Lyon president Jean-Michel Aulas confirmed on Sunday that Arsenal were closing in on a deal for Lacazette, 26, that would represent a record fee for both clubs. Arsenal's previous record deal was the £42.4 million signing of Mesut Ozil from Real Madrid in 2013.
The deal is a massive boost to manager Arsene Wenger, who has finally landed the type of elusive top-class striker he has been seeking for years. Lacazette scored 37 times in 45 games last season, and has netted at least 20 league goals in each of the last three seasons.
Arsenal confirm Lacazette signing. In their own way... https://t.co/zPaKhv4GfA
- Mattias Karén (@MattiasKaren) July 5, 2017
A statement read: "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."
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 is Arsenal's second signing of the summer after Schalke left-back Sead Kolasinac joined on a free transfer, and provides the club with the sort of big-money star fans have been calling for after a disappointing fifth-place Premier League finish.
Arsenal have talked up their ambition to win the league since handing Wenger a new two-year deal, with CEO Ivan Gazidis promising fans last week that the club was pursuing "top quality" players who could strengthen the team immediately.
Lacazette had been set to join Atletico Madrid until the Spanish club's transfer ban was upheld this summer, giving Wenger a second chance to sign a player he had initially bid for last summer.
Arsenal also made a bid for Monaco winger Thomas Lemar last month but were rebuffed by the Ligue 1 club, while their hopes of pulling off a world-record move for fellow Monaco star Mbappe look increasingly slim.
However, Lacazette should give the team's attack an immediate upgrade and could form a formidable front three with Alexis Sanchez and Mesut Ozil if they stay at the club.
Neither Sanchez nor Ozil has agreed a contract extension with their current deals due to expire next summer.