The showrunner told SFX that two four-minute mini-episodes will air throughout the BBC's charity telethon on March 18.
"It's not a spoof," he insisted. "It's in the style of the ones that we've done for Children In Need, so it's taken seriously as a proper bit of Doctor Who. [It's] funny, but not a sketch."
Moffat also revealed that two different versions of companion Amy Pond will appear in the two instalments, which are titled 'Space' and 'Time'.
"There's a moment with two Amy Ponds in it," he confirmed. "If you're a red-blooded male, surely that's enough! You've got Amy Pond flirting with herself."
He added that the specials will feature just the show's regular cast of Matt Smith, Karen Gillan and Arthur Darvill.
"There isn't a guest character, it's just the three of them," he explained. "A moment of life aboard the Tardis. But obviously life about the Tardis instantly gets you into terrible jeopardy, and all of causality is threatened."
Comic Relief: Funny For Money on Red Nose Day begins on March 18 at 7pm on BBC One.