Richard Coyle and Claire Foy have landed the lead roles of arch-swindler Moist Von Lipwig and Adore Belle Dearheart respectively. They will be joined in the production by David Suchet as Reacher Gilt and Charles Dance as Lord Vetinari.
Additionally, Steve Pemberton will portray Drumknott, Andrew Sachs will be Groat, and Miss Crisplock will be played by Tamsin Greig.
"Following the Sky1 HD successes of Sir Terry Pratchett's Hogfather and The Colour of Magic, we're thrilled to now be bringing Going Postal to life," said head of Sky1 drama Elaine Pyke.
"Adapted by Richard Kurti and Bev Doyle, Going Postal is a hugely enjoyable epic adventure story guaranteed to delight audiences across the country next Easter."
Production has now started on the two-part series, which is due to broadcast in spring 2010.