The six-part series, titled Strike Back, also features Andrew Lincoln, Jodhi May, Orla Brady, Laura Greenwood and Nicola Stephenson.
The drama follows the lives of two former soldiers, Major Hugh Collinson (Lincoln) and discharged veteran John Porter (Armitage), as they're about to meet for the first time in seven years in a Middle East hostage crisis.
"As with all Sky1 dramas, not only will it feature a gifted cast with a large popular following, but working with Andy Harries and Left Bank Pictures means an already crackling script will jump out of the screen," said Sky1's Elaine Pyke.
"Shot in South Africa with stunning locations and high octane HD action sequences on a grand scale, Chris Ryan's bestselling novel will be a truly uncompromising, compelling, action drama."
The series is due to air in spring 2010 on Sky1 and Sky1 HD.