The local group was one of six British chambers included in a joint letter to UK transport secretary Grant Shapps.
Under the plans, the main runway and emergency runway would both be used, with the latter for smaller aircraft taking off.
The main runway would still be used for all arrivals.
The joint letter is signed by groups from Belfast, Aberdeen, the Isle of Man, London and Sussex, as well as local chamber executive director Kay Leslie.
‘Gatwick is a vital piece of national infrastructure that for many years has provided investment and commercial opportunities for our members and the organisations we represent,’ the letter said.
‘We are writing in support of Gatwick’s proposal to utilise the existing northern runway in scheduled operations, as we believe that the additional capacity created will support regional connectivity and so support the [UK] government’s Levelling Up agenda, especially where rail is a not a practical alternative.’
Between the six groups, they represent 8,500 members.
Gatwick has returned to being Guernsey’s busiest route following the pandemic, with more than 53,000 journeys made on the route so far this year.
The airport is also proposing road improvements, realignment of the northern runway, a new pier, additional parking and hotels and improvements to the existing terminal buildings.
n The consultation ends at midnight tonight. It can be viewed at https://bit.ly/3xAilJi.
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