The Price Tag singer said that having no hair was 'the weirdest feeling' and proudly rocked the look on stage on the BBC live show.
After having her hair cut, Jessie emerged to speak to hosts Dermot O'Leary and Claudia Winkleman about how she was feeling.
As Dermot stroked her head she said: 'That feels nice,' adding, 'It feels liberating.'
While Dermot and Claudia wanted to know how Jessie was feeling, she was eager to encourage viewers to donate to Comic Relief.
She revealed her family were backstage crying and appealed to the audience to raise money.
Shock: Jessie J took her shaved head in her stride making the point it was all for charity
She looks fab! The 24-year-old singer looked fabulous as she emerged on stage with her newly shaved head
Hair today gone tomorrow: Jessie was still smiling after she had her head shaved just moments earlier she was showing off her glossy dark locks
Earlier in the evening Jessie spoke about why she decided to chop off all her hair, her jet black bob and fringe have been her signature style since she shot to fame.
She said: 'This programme started when I was born.'
Jessie added that she wanted to: 'Shock people. I wanted to do something that wasn't going to last five minutes and it's fun.
She's done it! Jessie stepped out on stage after successfully completing her head shave. She appealed to viewers to donate
Here she is: Jessie strutted out onto the stage in a cropped top and high-waisted trousers
Just her bangs left: The camera cut to Jessie half-way through her shave when just her signature fringe was left
'I'm selling this on Ebay: Lenny joked that he would try and flog Jessie's cuttings
Claudia told her: 'You're a great girl.'
After appearing on the show Jessie didn't waste time thanking fans and tweeted: 'I am soooo thankful to everyone who has donated @rednoseday and supported me tonight! My heart is filled with happiness! Lets make a change! X'
During the programme a segment aired showing Jessie visiting some of the charities that Comic Relief helps.
