He denied the act of foul play but was found guilty by the citing commissioner and will miss Samoa’s last match against Scotland on Sunday.
It means he will not be available for Samoa’s final pool fixture against Scotland on Saturday and will not be available to turn out for his Newcastle Falcons club side before November 10.
Given his age, this year’s tournament is expected to be his global swansong.
Following a review of video footage, Tuilagi was cited for striking Japan player Harumichi Tatekawa with his knee during the second minute of their game at Milton Keynes.
ITV pundit and commentator David Flatman, a former prop for Bath and England, said: ‘Decisions like the one from @WorldRugby to ban Tuilagi are threatening to ruin this World Cup. Another RWC commission fail’.
The decision to ban Tuilagi for such a period has nevertheless been met with widespread surprise, with many believing the use of the knee was inadvertent – a few suggesting that Tatekawa, who was able to finish the match, positioned himself poorly to try and tackle the man with the ball.
Northampton fly-half and England global Ryan Lamb wrote: ‘Tuilagi’s ban is ridiculous, just put a belt on and call it the tag rugby World Cup‘. “Should we play walking rugby now!!!”