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 - 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 - who has also voiced Aslan the Lion in the movie adaptation of the `Chronicles Of Narnia` books - 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 - 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.