Jessie J admits that she was "pitchy" at her X Factor performance last week.

The 23-year-old singer received harsh criticism for her off-key performance on the British reality television contest.

Jessie realises that she was out-of-tune, but she is proud of her mistakes.

"I was on X Factor on Sunday. Afterwards I went on Twitter, and so many people were attacking me because I was pitchy," Jessie said at the BBC Radio 1Xtra Live in Brixton concert in London Thursday.

"[The performance] was out of tune, but I've never mimed and I'm proud of that."

Jessie grows exponentially from the mistakes she makes.

She does not surround herself with sycophants, as she needs people to call her out on her errors.

"I would never surround myself with people who tell me I'm perfect because I'm not and I don't want to be," Jessie explained.

Jessie is comfortable with the knowledge that she is imperfect.

Slight slip-ups every now and then do not adversely affect her self-confidence.

"I'm 23, and sometimes I sing out-of-tune. Sometimes I say stuff that I shouldn't, and sometimes I'm going to make mistakes."

The British songstress was recently named as a coach and a mentor on upcoming television series, The Voice UK.

She will join producer and Black Eyed Peas musician Will.i.am on the coaching panel.