Last night (Sunday) Wightlink's Victoria of Wight boat returned to service.
The ferry firm had predicted she would be up and running again tomorrow (Tuesday).
The boat was taken out of service to carry out engine repairs and maintenance nearly a month ago (15 June).
It caused chaos for travellers with amended sailings and cancellations.
A spokesperson for the ferry firm has apologised:
'We are sorry many bookings had to be changed to enable all customers to cross the Solent, including freight companies taking essential supplies to and from the Isle of Wight.'