Metrobus will be closing its base in Lewes at the end of July, leaving staff to find new jobs. The company cited commercial reasons.
Metrobus has given notice to Brighton and Hove City Council and East Sussex County Council to terminate all its contracted tendered bus services from Lewes.
City council officials have said they will assign the contracts for the 47 and 56 bus routes to Brighton and Hove Bus and Coach Company so there will be no change for passengers other than the colour of the bus.
East Sussex County Council will review tendered routes before putting them out to retender.
This includes some school buses to Tideway School in Newhaven and Cardinal Newman School in Hove as well as bus routes between Peacehaven, Newhaven and Lewes and others in the Seaford area.
More than 20 drivers are based at Lewes.
They are being offered alternative jobs at Metrobus, which has a garage in Crawley plus others in Surrey and Kent.
Staff can also transfer to Brighton and Hove Bus and Coach Company. Those who do not want to accept these jobs will be made redundant.
Metrobus managing director Alan Eatwell said: "We regret having to make this decision, which is disappointing as our workforce has been very conscientious.
"The economics of the operation at Lewes are not adequate.
"We are trying to find alternatives with the help of Brighton and Hove or elsewhere with Metrobus."
Both Metrobus, which has dark blue buses, and Brighton and Hove are part of the parent group, Go Ahead.
Monday June 2, 2003