The aim of the match is to raise money to help the care and rehabilitation of injured British service personnel who have served in Iraq and Afghanistan.
England team manager and rugby legend Johnson will line up alongside captain Lawrence Dallaglio for the first time since 2003 to play for the Help for Heroes XV against an International XV managed by Ieuan Evans and captained by Scott Gibbs.
Johnson said: Ive kept myself fit and, although Ive played some charity rugby and football matches, this will be the first and Im sure the last time that I will play in a competitive match against some world-class players.
As soon as I was asked to play by Lawrence Dallaglio, I didnt hesitate to say yes.
The cause is a superb one and anything the players and fans can do to raise money for care and the facilities to support our wounded service personnel at Selly Oak and Headley Court has to be worthwhile.
Our target is to reach a sell-out at Twickenham and to raise £1million for Help for Heroes so I urge everyone to do their bit, buy a ticket and enjoy a good day out for an excellent cause.
Further details of players who will take part in the Help for Heroes match will be announced next week.
Tickets for the Help for Heroes match on Saturday, September 20 are available from Ticketmaster by calling 0844 8472492 or by contacting ticketmaster.co.uk. Tickets are £20 for adults, £10 for under 16s, a family ticket for two adults and two children costs £50.