Lead colourisation artist Rich Tipple and his team spent 12 months working on the project.
He said: “Some people find black and white a barrier to watch.
“Making this in colour is a chance to open it up to a whole new audience who can now appreciate how good the 1960s golden era of Doctor Who was.”
The War Games was filmed extensively in East Sussex locations including Brighton, Cuckmere and Birling Gap.
Mr Tipple said: “It was a joy to work on something that had such amazing links to where I’m from.
“It was magic to be able to turn locations that I’m so familiar with into vibrant colour.”
The episode will feature the Second Doctor’s never-before-seen regeneration into the Third Doctor (Jon Pertwee), alongside recovered footage not seen since the original broadcast.