A total of 165 countries – 19 more than at Beijing 2008 – will take part in the competition, with the number of athletes set to increase from 3,951 to around 4,200.
IPC President Sir Philip Craven said: 'It's fantastic news to mark 100 days to go that we can announce that the London Games will be the biggest ever.
'The Paralympic Games continue to grow in size and stature each edition and it is even more pleasing that Great Britain, the spiritual birthplace of the Paralympic Movement, will get to host the biggest ever Paralympic Games later this year.'
Sixteen countries are set to take part in their first Paralympic Games at London 2012. They are Antigua & Barbuda, Brunei, Cameroon, Comoros, Djibouti, Democratic Republic of Congo, Gambia, Guinea-Bissau, Liberia, Malawi, Mozambique, North Korea, San Marino, Solomon Islands, Trinidad & Tobago and US Virgin Islands.
Tickets on general sale
In addition to a record number of athletes and countries taking part, more than one million tickets, an unprecedented number so many months ahead of a Games, were sold last September. Tickets will go back on general sale from 11am on Monday 21 May.
The London 2012 Organising Committee (LOCOG) recently announced a record-breaking collection of Rights Holding Broadcasters who will screen the Paralympic Games across the globe this summer. The total worldwide broadcast deals for the London 2012 Paralympic Games will see a record £10 million in revenue generated from the sale of broadcast rights, with an estimated cumulated audience of around four billion people.
Today's milestone has also been marked by LOCOG announcing that British band Coldplay will perform at the London 2012 Paralympic Games Closing Ceremony
Find out more on the IPC website