The Swainson Street business, which dates back to the end of the 19th Century, shared the news on social media on Saturday, June 6.
Official records also indicate that hotel owner Shepherd Cox Hotels (Hartlepool) has been placed into administration.
The town’s MP is now hoping that a new buyer can be found to save jobs.
It is unclear how many people have been made redundant.
Hospitality businesses have been hit hard by the covid-19 pandemic with lockdown measures meaning many have been entirely closed since March.
According to the London Gazette, which logs statutory public notices, administrators were appointed to Shepherd Cox Hotels (Hartlepool) at the end of last month.
A statement posted onto the hotel’s official Facebook page said: “Dear valued patrons. I am receiving a number of calls today regarding the status of the hotel.
“It is with regret that I must confirm the hotel is now in administration with all employees (including myself) made redundant yesterday (Friday, June 5).
“I am sure that someone will be in touch in the coming days with regards to weddings and events that have been booked, but unfortunately it is out of our hands at this point so calling the hotel directs to my mobile, and I am afraid I am unable to tell you anything more.
“Best wishes ... we will miss you. Paul (Ex General Manager).”
Earlier posts on the same Facebook page said the team at The Grand had been providing Sunday lunches for collection or delivery during the lockdown.
Hartlepool MP Mike Hill said: “In these difficult times this is a devastating blow, not only for the hotel, but for Hartlepool. It creates uncertainty.
“It’s bad news for the trade and doesn’t bode well for the travel economy in the future.
“I’m very concerned about the economic impact on the town of closures like this, especially at a time when we’re looking for recovery post-Covid-19.
“My thoughts are also with those who made advance bookings with Best Western; weddings and other functions.
“I hope a buyer can be found soon and that people can somehow keep their jobs.”