Passengers using Gatwick last month increased marginally against September last year with rise of 14,800 or 0.3% to 4.5 million.
However, long-haul growth was up by more than 18% in September with the help of routes to Rwanda and Hong Kong.
In short-haul Vienna achieved 130% growth due to a new service by low cost carrier Level introduced earlier this year.
Edinburgh was the domestic route with the highest growth rate, rising by 5.9% year-on-year.
The Carbon Trust named Gatwick the UK airport with the biggest combined reduction of operational carbon, water and non-recycled waste last year.
Virgin Atlantic last week ran the world’s first commercial transatlantic flight to use next generation fuel made from recycled waste carbon gases.
Gatwick CEO Stewart Wingate said: “Sustainable growth remains a top priority at Gatwick.
“It’s therefore encouraging to achieve another month of healthy growth in passenger numbers, while at the same time being recognised for our commitment to reducing carbon, water and non-recycled waste on-site.
“Ensuring Gatwick has the capacity to grow sustainably in the decades to come is the key to a prosperous future for the south- east and the UK as a whole.
“With our long-haul network thriving, we’re in a strong position to support a post-Brexit Britain, when long-haul connections to countries like China will be more important than ever before.”