Newcastle announced Charnley's new role on Monday, after he previously held the role of football secretary at St James' Park, as well as being a director since 2008.
The role of managing director was previously held by Derek Llambias, who resigned his position in June 2013, shortly after Joe Kinnear had been appointed director of football, though he too has since departed the club.
In a further reshuffle, owner Mike Ashley has been officially appointed onto the club's board of directors, alongside Charnley and finance director John Irving.
Charnley stated that transfer plans for the close-season have already begun, with fans looking for reinvestment from the reported £20million fee received for star midfielder Yohan Cabaye in his sale to Paris Saint-Germain.
However, Charnley has stressed the importance of financial prudence and said the club will continue to work hard to get the best deal from every transfer.
"Our preparations for the summer transfer window have already begun of course, and our challenge is to make sure we spend the funds we have available in a careful and considered way in order to ensure that we get the maximum benefit from every pound we invest in the squad," Charnley said.
"We will continue to operate in a financially responsible manner and live within our means. This club is financially strong and there is money to spend if the deal is right and we are confident a player can add quality to the squad.
"That said, we will not pay over the odds or make knee-jerk decisions. Every player we sign represents a major investment and mistakes are costly which is why we will continue to be prudent in our transfer dealings.
"This is the reality of a well-run football club like ours.
"As a board we will continue to make the final decisions on all player transfers. Clearly however the manager and his team have a very significant involvement in such decisions and will be instrumental in making recommendations in relation to the squad.
"Our transfer policy and strategy is very clear and will remain unchanged. We will focus on identifying and recruiting young players whose best years are ahead of them, which in nearly all cases means players in their early to mid-20s and not beyond."
