Aurigny has announced it will drop the route in October, saying it regularly operates at less than half capacity and was making a loss.
However, the Institute of Directors Guernsey branch has joined the likes of the Guernsey International Business Association and the Chamber of Commerce in speaking out against the decision.
'From the IoD's perspective it is incredibly disappointing that Aurigny have chosen to terminate the London City route, given the diversification and additional European connections it offers,' said chairwoman Linda Johnson.
'In a 2016 survey, the LCY route was rated the third-most important for Guernsey IoD members, behind Gatwick and Jersey, however unfortunately this has not been reflective of the actual level of usage of the route.
'Whilst we need to be pragmatic about the economic sustainability of the LCY route, without putting on any additional capacity to Gatwick at the peak business times, the loss of the route materially reduces early morning and evening seat capacity, exacerbating existing issues with seat availability at peak times.'
Mrs Johnson said the IoD will support Economic Development in their endeavours 'to identify other, more efficient models or operators for the London routes'.
