P&O said that income generated by ticket sales did not cover the costs of the Irish Sea route, despite efforts to find savings.
The company said it had to face the “stark reality” that the 13-year-old service was no longer viable, but insisted there would be no job losses as a result of the decision.
In the wake of the move, P&O said it would continue to operate its Cairnryan service to the Northern Irish port.
The company said the decision to axe the Troon service, which did not operate in the winter months, came after a “comprehensive review.”
There have been doubts over the future of the route since last June, when P&O announced it would not be renewing the hire of its Express ship for 2016. The chartered catamaran, which had operated out of Larne since 2006, was relocated to Sweden.
At the time, P&O insisted it was “a ship decision, not a route decision,” but in a statement yesterday, it emerged that efforts to find a new vessel had been “unsuccessful”.
The firm said: “P&O Ferries has proudly operated this additional seasonal route, but the stark reality is that the company is continuing to make significant losses, and sadly the income from ticket sales is not sufficient to cover the annual vessel and port operating costs.
“In a final attempt to make the route economic the company reduced the service in the off-peak months last year, whilst maintaining the full service in the peak months of July and August. Whilst this measure did significantly reduce the operating costs, the route remained loss-making.”
The statement added: “Since the last sailing at the end of September, P&O Ferries has continued to negotiate with a number of suppliers and other organisations, including the search for a lower cost chartered fast-craft to be able to continue, but we have been unable to develop a solution for the company.
“There will be no redundancies, with all permanent staff being found alternative roles within the company.”
The Larne to Troon service opened in 2003.