The 15-year-old won favourite singer and favourite TV actress for her role in Disney series Hannah Montana.
Harrison Ford, Cameron Diaz, Usher, Heidi Klum and Orlando Bloom were among the big names who ended up covered in the ceremony's trademark green slime.
Johnny Depp was voted favourite actor, while Diaz won the "Wannabe" prize for being a celebrity children look up to.
After urging the 10,000-strong audience to "change the world", she described the award as "the biggest honour of my entire life", even beating her previous Kids' Choice gong for burping.
Eddie Murphy was recognised for his voice work in Shrek the Third, American Idol won favourite reality show and the Jonas Brothers triumphed in the music group category.
The ceremony was hosted by actor Jack Black for the second time.
The winners in full:
Alvin and the Chipmunks - WINNER
Are We Done Yet?
Pirates of the Caribbean: At World's End
Ratatouille - WINNER
Shrek the Third
The Simpsons Movie
Male Movie Star
Ice Cube (Are We Done Yet?)
Johnny Depp (Pirates of the Caribbean: At World's End) - WINNER
Dwayne Johnson (The Game Plan)
Eddie Murphy (Norbit)
Female Movie Star
Jessica Alba (Fantastic Four: Rise of the Silver Surfer) - WINNER
Drew Barrymore (Music and Lyrics)
Kirsten Dunst, (Spider-Man 3)
Keira Knightley (Pirates of the Caribbean: At World's End)
Cameron Diaz (Shrek the Third)
Eddie Murphy (Shrek the Third) - WINNER
Mike Myers (Shrek the Third)
Jerry Seinfeld (Bee Movie)
Drake & Josh - WINNER
The Suite Life of Zack and Cody
America's Next Top Model
American Idol - WINNER
Are You Smarter Than a Fifth Grader?
Deal or No Deal?
Drake Bell (Drake & Josh) - WINNER
Josh Peck (Drake & Josh)
Cole Sprouse (The Suite Life of Zack and Cody)
Dylan Sprouse (The Suite Life of Zack and Cody)
Miley Cyrus (Hannah Montana) - WINNER
Emma Roberts (Unfabulous)
Jamie Lynn Spears (Zoey 101)
Raven-Symone (That's So Raven)
Avatar: The Last Airbender - WINNER
Ed, Edd and Eddy
'Beautiful Girls' (Sean Kingston)
'Big Girls Don't Cry' (Fergie)
'Don't Matter' (Akon)
'Girlfriend' (Avril Lavigne) - WINNER
Chris Brown - WINNER
Miley Cyrus - WINNER
Boys Like Girls
Fall Out Boy
Jonas Brothers - WINNER
Tony Hawk - WINNER
Danica Patrick - WINNER
Dance Dance Revolution
High School Musical: Sing It!
Madden NFL '08 - WINNER
Buffy the Vampire Slayer Season Eight, Volume One: The Long Way Home
Diary of a Wimpy Kid
Harry Potter series - WINNER
How to Eat Fried Worms