Jo, who played EastEnders favourite Tanya Branning, debuted her brown hair this morning (24 April) during an appearance on Lorraine.
We had to do a double take, as the actress looks so different from the blonde we were used to seeing in Albert Square!
Jo was appearing on Lorraine to chat about life after EastEnders and admitted that her change in hair colour was an act of teenage rebellion AND for a new role!
She said: "I've had a little makeover! I've been a bit teenage actually, I'm getting to play with my hair for once. It's like when I used to have temporary dyes as a teenage and would work through every colour!"
Explaining the reason behind her brunette tresses, Jo added: "It's one part being a bit teenage and having a go at something new, and then I'm doing a BBC eight-parter at the moment and have gone a bit darker for that."
Jo was referring to The Interceptor, an upcoming drama that also stars David Gyasi. The hour-long episodes will follow the UNIT - an elite surveillance team who track dangerous criminals.
She is also set to appear in Trying Again, a new comedy about a couple who are giving their marriage another go following an affair.
The show kicks off tonight on Sky Atlantic and you can read more about it here!
Do you like Jo's new look? Tell us below, as the best comment from across the website each week wins £50!