Zachary Gordon as Greg Heffley

Robert Capron as Rowley Jefferson

Steve Zahn as Frank J. Heffley

Devon Bostick as Rodrick Heffley

Rachael Harris as Susan Heffley

Chloë Grace Moretz as Angie Steadman

Laine MacNeil as Patty Farrell

Andrew McNee as Coach Malone

Connor Fielding as Manny Heffley

Owen Fielding as Manny Heffley

Karan Brar as Chirag Gupta

Grayson Russell as Fregley

Alex Ferris as Collin

Belita Moreno as Mrs. Norton

Rob LaBelle as Mr. Winsky

Nicholas Carey as Pete Hosey

Samuel Patrick Chu as Carter

Donnie MacNeil as Wade

Samantha Page as Shelley

Ava Hughes as Marley

Owen Best as Bryce Anderson

Cainan Wiebe as Quentin

Cole Heppell as Quentin's Sidekick

Harrison Houde as Darren Walsh

Severin Korfer as Dieter Muller

Jennifer Clement as Mrs. Flint

Karin Konoval as Mrs. Irvine

Raugi Yu as Vice Principal Roy

Kaye Capron as Rowley's Mom

Jake D. Smith as Archie Kelly

Talon Dunbar as Arthur

Naomi Dane as Cheese Girl

Willem Jacobson as Cheese Boy

Sean Bygrave as Coach Brewer

Maxine Miller as Elderly Woman

Taya Clyne as Granddaughter

Nathaniel Marten as Grown-Up Greg

Peter New as Grown-Up Quentin

Nikki Frazer as Lunch Girl #1

Greta Makena Gibson as Lunch Kid #2

Nathan Smith as Kindergarten Boy

Kinua McWatt as Kindergarten Girl

Dylan Bell as Kindergarten Greg

Madison Bell as Kindergarten Patty

Adom Osei as Marty Porter

Alf Humphreys as Mr. Jefferson

Brent Chapman as Mr. Parnell

Rylee Stiles as Preston

Ryan Grantham as Rodney James

Ethan Shankaruk as Snot Kid

Jesse Wheeler as Unpopular 80s Boy

Paul Hubbard as Brock Branigan

Brett Dier as 80s Breakdancer

Brandon Barton as 80s Jock Boy

Cindy Busby as 80s Popular Girl

Alicia Takase Lui as Audition Kid

Jay Sidhu as Audition Kid

Tori Christianson as Audition Kid

Emerald Schreier as Audition Kid

Ben Mitchell as Audition Kid

Haris Cash as Audition Kid

Mariah Crudo as Audition Kid

Alistair Abell as Male Reporter (voice)

Tara McGuire as Female Reporter (voice)

Aidan Gebert as Löded Diper

Cameron Krpan as Löded Diper

Paolo Tolfo as Löded Diper

Amy Esterle as Waitress (uncredited)

John Cygan as Parent (uncredited)