Sarah Fenton, 39, was last seen by her husband on board the boat at 5.30pm on Sunday and a plane and lifeboats mounted a search for her that lasted until 10pm.
The family of the woman from Fishponds, Bristol, were said to be 'very concerned', as police appealed for urgent help from the public.
The search of the English Channel has been called off as the investigation continues.
Detective Inspector Becky Riggs said: 'Sarah's family are very concerned about her and we are investigating the circumstances surrounding her disappearance.
'I am appealing to anyone who may have seen Sarah on board the ferry to contact me urgently. Anyone with information should call us as soon as possible.'
The ferry left Jersey at 2.30pm before travelling to Guernsey and departed for Poole, Dorset, at 4.15pm. Read More