Disney recently confirmed that the fourth and final season is in production and will premiere in late spring with enough episodes to last until 2011.
Speaking to E!'s Ryan Seacrest on the red carpet at last night's Grammy Awards, she said: "It's really cool the way we're doing it.
"It's not like shows that end and you see reruns over and over. We're giving it a definite ending because it deserves it."
When asked if she was sad about leaving the character, she replied: "Yeah. Everyday I come to work we'll get frustrated and like, 'Is this right? Is this how we want to end it? What do we want to do?'.
"We're like, 'Let's make the best decision we can as a family'. It's so important, those last few times together, to make it the most important time, spend it with each other and love on each other."
Cyrus introduced the Black Eyed Peas at the annual ceremony and has confirmed that she will be auctioning her Herve Leger outfit to help the Haiti earthquake relief fund.