Mountain Warehouse, on Flowergate, shut on Sunday afternoon when its management was told one of the team had the virus.
A deep clean has taken place and it plans to reopen today.
A spokesperson for Mountain Warehouse said: "We temporarily closed our Whitby store on Sunday afternoon following notification of a case of Covid-19 among one of the team there.
"The colleague concerned is now self-isolating at home for the recommended 14-day period and we wish them well with their recovery.
"The colleague had not been in the store since last Wednesday owing to pre-booked leave.
"All colleagues who were in close contact have already been, or are in the process of being tested before they can return to work – subject to receiving a negative test result.
"The store is being deep-cleaned and we plan to re-open today.
"The safety of our staff and customers remains our priority and we will continue to follow the official advice and guidelines.”
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