The NHL announced the discipline Tuesday night for Lemieux, who will forfeit $38,750 in salary while under suspension. The league posted video and a release on the NHL Player Safety page on Twitter.
The bite happened late in the third period of the Kings' 4-2 win last Saturday at Staples Center. Lemieux was prone on the ice and wrestling with Tkachuk and a linesman when he bit Tkachuk on the right hand.
Lemieux received a match penalty for his actions. Tkachuk was furious afterward, calling Lemieux's actions "the most gutless thing somebody could ever do."
"Kids don't even do that anymore. Babies do that," Tkachuk added. "I don't even know what he was thinking. He's just a complete brick head. He's got nothing up there. Bad guy, bad player, what a joke he is."
The 25-year-old Lemieux is the American-born son of infamous NHL agitator Claude Lemieux, while Tkachuk is the son of NHL veteran Keith Tkachuk, who racked up 2,219 penalty minutes in his two-decade career.
Brendan Lemieux joined the Kings last March in a trade with the New York Rangers. He has four goals, one assist and 32 penalty minutes -- 14 against the Senators -- in 14 games this season for LA.
The Kings hosted the Anaheim Ducks on Tuesday night.
It's been a tough run for the Senators, and this incident plays along with that as something a young team simply have to overcome. Ottawa is in last place in the Atlantic Division at 4-14-1.
"We're not going to look back or be negative about anything," Senators coach D.J. Smith said Tuesday. "We're going to be positive about everything going forward."
The Associated Press contributed to this report.