All proceeds from the game, which kicks off at 4pm, will go the South Atlantic Medal Association charity (1982) which is based in Blackwood, Gwent.
The teams taking to the field will include some Welsh born soldiers who are following in the armed services footsteps of their Task Force predecessors.
The match will be followed by a commemorative dinner at the Twickenham Stoop where guests will include the Welsh Falklands Veteran Simon Weston. The match which will also feature some cameo game time for at least three Falkland veterans.
This summer, a series of national UK events are being held to mark the 25th anniversary of the Falklands War.
In 1982 a Task Force of 28,000 men and more than 100 ships headed 8,000 miles for the South Atlantic to fight a three and a half week long campaign in which 255 British troops and three Falkland Islanders died.
More details on the London game can be seen on the organisers' website: www.falklandstaskforcerugby.co.uk