The 'Schindler's List' actor will be shows as a full body hologram narrating the musical, which will be staged on an arena tour across the UK next year.
The star takes over from the late Richard Burton, who's distinctive voice was used to narrate the 1978 soundtrack album of the musical â based on HG Wells' classic science fiction tale of aliens invading earth - and has been used, along with a holographic head, in the production since 2006.
Liam said he is honoured to be taking over the role of George Herbert, the story's narrator, for the production.
He told BANG Showbiz: "I was very flattered to be offered the role. I loved Richard Burton and I loved his voice."
Liam â who has also voiced Aslan The Lion in the movie adaptation of the 'Chronicles Of Narnia' books â said he worked closely with Jeff Wayne, who composed the original soundtrack, to get a new take on the role.
He added: "I had to put [Richard's version] aside and focus on the text and listen to Jeff and the director.
"We've tightened up the grooves, we've added to it, without taking away from the main compositions, and there's a new context for the singing and acting and some new ingredients."
Jeff has also produced a new version of the album, which will accompany the stage production.
Liam will appear in the stage show in three guises â as a full body hologram, as a 3.5 metre tall holographic floating head and shoulders, and as part of a two hour CGI film, which accompanies the production.
'War of the Worlds' stage tour of the UK December 2012, confirmed dates:
Saturday 01 Liverpool Echo Arena
Sunday 02 Cardiff Motorpoint Arena
Tuesday 04 Nottingham Capital FM Arena
Thursday 06 London Wembley Arena
Friday 07 Birmingham NIA
Saturday 08 Manchester Evening News Arena
Sunday 09 Sheffield Motorpoint Arena
Monday 10 Newcastle Metro Radio Arena
Tuesday 11 Glasgow SECC
Thursday 13 Bournemouth BIC
Saturday 15 London O2 Arena
Sunday 16 Brighton Brighton Centre