Kelly Osbourne has thanked her ''perfect'' mother for always being there for her.

The 29-year-old star has written a heartfelt letter to her mother Sharon Osbourne, wishing the former 'X Factor' judge a happy mother's day and thanking her for her continued support, despite admitting she was often ungrateful in the past.

Writing on her official website, she said: ''Thank you for all the sacrifices you have made in order for me to have a better life. Thank you for never giving up on me when I blamed you for everything I was doing wrong.

''Thank you for teaching me what love is and guiding me to become the person I am today. I am the person I am today because of you.''

The E! 'Fashion Police' critic also apologised for trying to push her mother - who is married to Black Sabbath rocker Ozzy Osbourne - away and confessed she's happy she's grown to be more like her.

She wrote: ''You are the beautiful, kind, generous, loving and let's not forget strongest person I have ever met and the best part is that you are MY mum.

''I may not be exactly like you but if there is anyone in this world I am most alike it is you Mumma, and I am so proud to be your daughter.''

Kelly did joke, however, that there is one thing her mum didn't teach her, and she's happy about that.

She said: ''The only thing you never taught me was how to cook! (I really am grateful that YOU never taught me because I probably would have poisoned someone by now.) (sic)''