800 people from the company were let go with immediate effect via a video call yesterday.
The company says its current business model isn't sustainable - and its made the decision to survive after considering all options.
An emergency meeting of Northern Ireland's economy committee's been called for this afternoon to discuss the situation.
Stormont's Infrastructure Minister Nichola Mallon says it is a disgrace while unions in Britain insist they're actively preparing to take legal action against the company.
Meanwhile, customers of P-and-O are being warned to expect further travel disruption for the next few days.
