Sir Chips Kewsick was on Friday appointed to the post after Peter Hill-Wood, 77, decided to stand down from the board after suffering a heart attack last year. The new boss, who has been on the Arsenal board since 2005, the last year in which the club won a trophy, will work closely with chief executive Ivan Gazidis at a critical time in the club's history.
Keswick immediately put the onus on delivering triumph. He said: "This is one of the great clubs in the game, recognised and loved by millions. I am looking forward to leading the club to future success."
The move breaks an 86-year bond with Arsenal. Hill-Wood had been at the helm since 1982 and his father Denis and grandfather Sir Samuel ran the club before him in a family dynasty stretching back to 1927.
Keswick, 73, a former director of the Bank of England and former chairman of Hambros Bank, could have a busy summer as Wenger has been predicted to spend serious money for the first time in years with Manchester United's Wayne Rooney and Real Madrid's Gonzalo Higuain having been linked with the club.
Sir Chips, full name Sir John Chippendale Lindley Keswick, is an old Etonian and is currently a non-executive director of a number of companies, including DeBeers Sa, Investec Bank and Persimmon plc.
Arsenal majority owner Stan Kroenke said: "I am delighted that Sir Chips has agreed to become chairman. He has a well respected track record in business and he will provide further direction and support in our ambition to compete at the top of the game here and in Europe and to win trophies."
Hill-Wood will be best remembered for driving through Arsenal's move from Highbury to the Emirates Stadium.
He said: "This has been a difficult decision as Arsenal football club has been a huge part of my life. Although I am feeling better I feel this is the right time for me to stand down."