The new requirement applies to all routes and ships, apart from departures from Guernsey, and will remain for the foreseeable future.
Safety measures are being tightened across its fleet following the recent increase in UK infection rates.
‘We took the decision to step up our safety protocols to protect those travelling on our ships and keep our freight supplies secure for the benefit of all islanders,' said Elwyn Dop, Condor operations director.
‘We fully understand that the changes may be inconvenient to some but are working in the best interests of the islands as a whole and feel this is the best option available to us.’
Passengers must have a negative PCR or lateral flow test to travel from the UK or France to Jersey or Guernsey, and from Jersey to Guernsey.
Commodore Goodwill will revert to carrying unaccompanied freight only from Portsmouth, to allow a sterile work environment.
This applies in Guernsey, Jersey, Portsmouth and St Malo.
Mr Dop said: ‘These are, once again, unprecedented times for our industry and these prudent measures ensure lifeline freight and passenger services are safeguarded. It is crucial that all the right steps are taken and we are in direct dialogue with both the States of Guernsey and Government of Jersey on this.’
All passengers will be notified of the changes, with bookings amended as appropriate.
Booking change fees will be waived for any travellers needing to transfer at short notice.
Condor CEO Paul Luxon responded to one complaint on twitter about the sudden announcement, with some passengers set to sail the day after they were told.
'Sorry for extremely short notice however with the Covid situation deteriorating around us at such a scary pace fast proactive action unavoidable to protect the essential daily supply chain for our islands + crew + passenger,' he said.
He said in another tweet that all protocols remain under daily review so they react swiftly in liaison with the public health teams in Guernsey and Jersey.
'Intention purely to protect and keep safe all even though travelling passenger numbers have been and are tiny now.'
There are currently five known active cases in Guernsey after four people recovered overnight and one new case was found through testing on arrival.
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