It is McDavid's first career suspension; he will forfeit $134,408.60 in salary.
The incident occurred late in the first period of Thursday's game against the Islanders. Leddy, who was trying to chip the puck into the Oilers' zone, was clipped in the head by McDavid's shoulder after releasing the puck, "making Leddy's head the main point of contact on a hit where such head contact was avoidable," according to a video released by the NHL Department of Player safety.
After the game, Islanders coach Barry Trotz said Leddy cleared concussion protocol.
McDavid would go on to score the overtime winner in a 4-3 victory.
The 21-year-old McDavid has just 88 penalty minutes in 267 career games.
"Obviously, it's not a great check," McDavid told reporters after the game. "It's not what I was trying to do. I wasn't trying to finish my check on him and he stopped a little earlier than I thought, and I hit him a bit too high."
McDavid, who leads the Oilers with 32 goals and 53 assists, will be eligible to return on Wednesday when Edmonton visits Toronto.