The 14.22 London to Paris service was delayed by an hour after it hit the animal in northern France.
A spokesperson for Eurostar said the incidence led to minor delays as temporary speed restrictions were implemented.
"The collision caused a few delays as the train was stopped to be checked," he said.
"After any collision we need to make sure everything is safe. There are wild boars in that area, which can take it upon themselves to roam from their area onto the track."
No one is thought to have been injured, but there was no further information about the boar, the BBC added.
Why a boar caused delays for Eurostar
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