Ina pop-history sense, yes. The last Norse invasion of England happened in the same year as its conquest by Norman knights.

If you mean at the time of the pagan Viking raids, then ehh, sort of, see JSheepherder's comment

Is there a particular meaning you attach to "knight?"

The word "knight," used to indicate a warrior, actually predates the Viking era. But if you bumped into one of the knights of Charlemagne you'd be forgiven for assuming from the chain armour, round shield, and the relatively short sword that he was a viking.