The Hammers face Italian side Fiorentina in their first European final in 47 years.
The club has an allocation of around 6,000 at the 19,360-capacity Fortuna Arena, but more than three times that number are expected to make the trip.
Supporters without a ticket will be able to watch the game at a fan zone in Letna Park, which has been designated for Hammers fans. The area will be large enough to host the thousands of ticketless supporters.
There is set to be a huge police presence, and Prague and West Ham have worked with local authorities to help ensure fans can congregate together safely.
The West Ham squad are due to fly out to Prague tonight and David Moyes will lead an open training session at the Sparta Academy, home of Sparta Prague youth teams, tomorrow.