The actress, 25, from Blackpool, has a string of acting credits to her name including Emmerdale, Waterloo Road and the upcoming ITV1 series Titanic.
Jenna says: "I'm beyond excited, I can't wait to get cracking; working alongside Matt I know is going to be enormous fun and a huge adventure."
Coleman has also said that she is a huge fan of the show, citing Billie Piper and Karen Gillan as her favourite companions.
Lead writer and Executive Producer, Steven Moffat, says: "It always seems impossible when you start casting these parts, but when we saw Matt and Jenna together, we knew we had our girl. She's funny and clever and exactly mad enough to step on board the TARDIS.
"It's not often the Doctor meets someone who can talk even faster than he does, but it's about to happen. Jenna is going to lead him his merriest dance yet. And that's all you're getting for now. Who she's playing, how the Doctor meets her, and even where he finds her, are all part of one of the biggest mysteries the Time Lord ever encounters. Even by the Doctor's standards, this isn't your usual boy meets girl."
Danny Cohen, Controller, BBC One, adds "As we approach Doctor Who's 50th anniversary it's great to welcome a new companion to the TARDIS. I feel confident the Doctor will look after her in his own very unique style."
Moffat has confirmed that six episodes will air in 2012 (including the Christmas Special), with a further eight being broadcast on BBC One in 2013.
Karen Gillan and Arthur Darvill will star in the first five of this year's episodes, and will depart before Coleman makes her début in the Christmas Special.
The Doctor will meet his new friend in a dramatic turn of events as the show builds towards its enormous, climactic 50th anniversary year - full of thrills, adventures and big surprises. Series seven is currently filming and comprises 14 big, blockbuster-movie episodes - each a brand new epic adventure featuring new monsters and some familiar foes as you've never seen them before.
Jenna-Louise Coleman starred in the 2011 movie Captain America: The First Avenger and has just finished shooting Stephen Poliakoff's Dancing On The Edge for BBC Two. The actress can be seen Annie Desmond in Titanic on Sunday at 9.00pm, ITV1.
(Sources: BBC Media Centre, BBC News)