The theme park will be twice the size of the Olympic Park, will create 27,000 jobs and be the third biggest theme park in the world - only if the special arachnids are removed.
An environmental audit of the 872-acre brownfield site in the Swanscombe Peninsula, Kent, has found it is one of two sites in the UK where the critters dwell. The spiders are protected on a biodiversity priority species list.
London Resort Company Holdings, the consortium behind the Paramount theme park will now have to find a new home for the colony.
The Paramount scheme, supported by Paramount Pictures, aims to create Europe's largest indoor water park with theatres, live music venues, attractions, cinemas, restaurants and hotels.
Tony Sefton, project director for LRCH, said there are plans to create a 27-acre wetland wildlife park on the site.
He said: "We will look after the spiders. We're doing a good thing."
He said LRCH hope to find a solution similar to that reached at the London 2012 Olympic Park where species found during development were moved to a wildlife sanctuary.
Dartford Borough Council leader Jeremy Kite said there are solutions to preserving unusual species.
He said: "In the past we've moved fish, we've sent voles away on holiday; it's fairly common and protects them from building works.
"Then when they're finished they're brought back."
The only other UK home for distinguished jumping spiders, which have the Latin name sitticus distinguendus, are the West Thurrock marshes in Essex.
The spiders are on the UK Biodiversity Action Plan priority species list, but it is not legally binding. But the list means the Joint Nature Conservation Committee has deemed the species threatened and one that requires conservation action. There is actually no law preventing developers building on the rare spiders' home.
There are 37 types of jumping spider in the UK, but worldwide it is the largest spider family, containing over 5,000 species.
They have a very large front pair of eyes, and are thought to possess the best vision for an invertebrate after cephalopods - octopus, squid and other molluscs.
This vision, along with an ability to jump, allows them to actively hunt their prey during the day.