The actors will depart their roles as The Doctor's companions Amy Pond and Rory Williams midway through the show's seventh run in 2012 in what was described as a "heartbreaking end".
Showrunner Steven Moffat confirmed at a press screening that Matt Smith's Time Lord will then be joined by "a new friend", who has yet to be cast.
"The final days of the Ponds are coming during the next series," he said. "I'm not telling you when or how, but that story is going to come to a heartbreaking end... Then The Doctor will meet a new friend."
Moffat added that he believes River Song (Alex Kingston) will make a return appearance, though it is unknown if the character will be involved in the couple's exit storyline.
It has been announced on the official Doctor Who Twitter profile that more details will be revealed tomorrow (December 16).
> Doctor Who Karen Gillan, Arthur Darvill's Amy and Rory exit reaction
Smith stated: "The show will miss the Ponds, brilliantly played by Karen and Arthur, but the great thing about Doctor Who is its ability to change.
"We had the most incredible journey. We took over the show and we've really had to hold hands and help each other through it.
"So it's very disappointing, but one has to remember that this show is about change and regeneration, and that's what galvanizes it and pushes it forwards."
Watch a video of Amy and Rory's wedding party from the end of series five below:
Gillan told Digital Spy in August that she expected to be a part of the sci-fi's seventh run.
Addressing Amy and Rory's potential departure last month, the actress said: "Death would be an option. I don't want Amy to pop up again every so often, because for me it would take away from the big, emotional goodbye. Once she's gone, she's gone. I want people to remember the Amy Pond era as a good one."
Gillan and Darvill both made their Doctor Who debut as Amy and Rory in the first episode of the show's fifth series in 2010.
Moffat revealed in November that Doctor Who's seventh series will air next Autumn.
Watch the trailer for the upcoming Doctor Who Christmas special - 'The Doctor, The Widow and The Wardrobe' - below: