The 'Domino' hitmaker took to Twitter to tell her fans of her charitable plans.
She tweeted: "I am SO excited and honoured to be able to finally officially announce I will be shaving my head LIVE for you ALL to watch in March 2013 for @rednoseday 😀 #letsraisesomemoney."
Jessie, who confirmed last month she'd be back The Voice UK next year, explained to her followers: "A year ago I said "I'm gonna shave my head for charity"...
"I have spent a long time making sure that when I do shave my head I raise as much money as possible for charity...
"I have been waiting for the perfect time and the right charity.. But also a charity that can get my amazing fans involved too.."
The 24-year-old said she planned to cut all of her hair off live on Comic Relief's Red Nose Day on Friday March 15 next year.
She added: "Follow @rednoseday please 🙂 & let's make next year's the BEST & most memorable but most of all it is "All about the money" (This time) ;).
"Be good. Do good. Feel good."