The late Easter school holidays in April gave Gatwick an additional 496,200 passengers.
Overall passenger numbers increased by 15% to 3.8 million, marking 50 months of consecutive growth.
Long-haul routes continued to grow with a 23% increase over the same month last year, led by New York, Los Angeles and Fort Lauderdale.
Top growing domestic routes were to Belfast, Jersey and Edinburgh as UK traffic grew by 10.7%.
Chief executive, Stewart Wingate, said: “Gatwick’s vital role for Britain shines through our latest traffic figures as the airport continues to go from strength to strength as we gear up for our biggest summer yet.
“Confidence in Gatwick is unrelenting as our existing carriers increase frequencies, Cathay Pacific will be providing a daily connection Gatwick to Hong Kong from June, and new routes are announced.
“We continue our trailblazing low-cost long-haul revolution, bringing more parts of the globe within reach of more Britons, with the world’s furthest low-cost long-haul connection just announced between Gatwick and Singapore, from Norwegian.
“Our booming long-haul routes have driven a huge cargo increase and at this crucial time for the country and the economy, Gatwick continues to stand ready and offers the UK Government a credible and deliverable option for runway expansion.”