The citing lodged by match citing commissioner Iain Goodall was for an alleged dangerous tackle on Perpignan player Dan Carter in contravention of Law 10.4 (e).
Ellis admitted he was guilty of foul play in that he had committed a dangerous tackle.
After considering the evidence available, the independent disciplinary committee comprising Professor Lorne Crerar, George Spotswood and Pat Barriscale determined that the offence was of the top end of the level of seriousness for a dangerous tackle.
Having taken into account any mitigating and aggravating factors the independent disciplinary committee suspended the player for a period of six weeks up to and including Sunday, January 25.
Both parties have the right to appeal.
A Leicester Tigers club statement said: “We are very disappointed that what we saw as a clumsy tackle has been characterised by the panel as an offence at the top end of the range of offending.
“We will consider an appeal in consultation with the club’s lawyers.”