Armitage was cited for making a dangerous tackle in England's 16-12 Pool B match against Scotland at Auckland's Eden Park last Saturday.
RWC Independent Judicial Officer Bruce Squire QC deemed Armitage's offence to be at the lower end of offending which has an entry point of two weeks.
The Judicial Officer took into consideration mitigating factors and the absence of aggravating factors in suspending Armitage for one match.
Armitage's suspension takes effect immediately and will include Saturday's quarter-final against France at Eden Park.
"It's a shame to lose Delon as he has played well but these things happen and we have some quality wings in Mark Cueto and Matt Banahan to choose from," England team manager Martin Johnson said.
Johnson also said injured key team members, fly-half Jonny Wilkinson (elbow) and centre Mike Tindall (bruised leg), were responding to treatment.
"We didn't train today but both are responding to treatment so we will just have to see where they are up to when we get back into weights and light training tomorrow," he said.
England's Armitage gets one-match ban
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