The ban, handed down by the disciplinary commission of the French Football League (LFP), applies to all official duties as well as stopping him from being present on the touchline during PSG games.
The Brazilian was found guilty of deliberately pushing referee Alexandre Castro in the tunnel following PSG's 1-1 Ligue 1 draw against Valenciennes on May 5, with the incident being caught on camera by Canal Plus television.
PSG responded by saying they will appeal the sanction.
In a statement the club described the suspension as "an unfounded decision and extremely severe" adding that they would remain "totally supportive of our sporting director".
Having regularly been outspoken in his criticism of match officials throughout the course of the season, Leonardo was furious at Castro's decision to send-off PSG captain Thiago Silva in the first half of the game.
Silva was shown a straight red card for lifting his hands to the referee as he protested a decision.
PSG were also handed a three-point deduction, although that part of the punishment is suspended.
The suspension could have serious consequences for the future of Leonardo at PSG.
It is believed that the French champions' Qatari owners had been considering the Brazilian former AC Milan and Inter Milan coach as a replacement for current boss Carlo Ancelotti, if the Italian gets the move away from the club that he wishes.
However, the length of the ban handed down almost certainly rules that out and is likely to have a major impact on his ability to carry out his duties as sporting director.
PSG's sporting director Leonardo handed nine-month ban
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