 | Danny DeVito als The Lorax (voice) |
 | Ed Helms als Once-ler (voice) |
 | Zac Efron als Ted Wiggins (voice) |
 | Rob Riggle als Mr. Aloysius O'Hare (voice) |
 | Taylor Swift als Audrey (voice) |
 | Jenny Slate als Mrs. Wiggins (voice) |
 | Betty White als Grammy Norma (voice) |
 | Nasim Pedrad als Once-ler's Mom (voice) |
 | Joel Swetow als 1st Marketing Guy (voice) |
 | Michael Beattie als 2nd Marketing Guy (voice) |
 | Elmarie Wendel als Aunt Grizelda (voice) |
 | Dave B. Mitchell als 1st Commercial Guy (voice) |
 | Dempsey Pappion als 2nd Commercial Guy (voice) |
 | Danny Cooksey als Brett / Chet (voice) |
 | Stephen Tobolowsky als Uncle Ubb (voice) |
 | Chris Renaud als Forest Animals (voice) |
 | Sherry Lynn als Additional Voices (voice) |
 | Mickie McGowan als Additional Voices (voice) |
 | Jack Angel als Additional Voices (voice) |
 | Bob Bergen als Additional Voices (voice) |
 | Debi Derryberry als Additional Voices (voice) |
 | Danny Mann als Additional Voices (voice) |
 | Fletcher Sheridan als Cy (voice) |
 | John Cygan als Additional Voices (voice) |
 | Bill Farmer als Additional Voices (voice) |
 | Jess Harnell als Additional Voices (voice) |
 | Mona Marshall als Additional Voices (voice) |
 | Laraine Newman als Additional Voices (voice) |
 | Jan Rabson als Additional Voices (voice) |
| Claira Nicole Titman als Additional Voices (voice) |
 | Jim Ward als Additional Voices (voice) |
| Chris Renaud | Director |
| Cinco Paul | Writer |
| Janet Healey | Producer |
| Ken Daurio | Writer |
| Chris Meledandri | Producer |
| Mitja Rabar | Animation |
| Cinco Paul | Executive Producer |
| Ken Schretzmann | Editor |
| Yarrow Cheney | Production Design |
| Massimo Ruberto | Music Supervisor |
| Steven Liu | Editor |
| Claire Dodgson | Editor |
| John Powell | Original Music Composer |
| Audrey Geisel | Executive Producer |
| Ken Daurio | Executive Producer |
| Fabrice Joubert | Animation |
| Eric Guillon | Character Designer |
| Catherine Catie Lee | Lighting Artist |
| Carter Goodrich | Character Designer |
| Randy Thom | Sound Designer |
| Dennis Leonard | Supervising Sound Editor |
| Kyle Balda | Co-Director |
| Dr. Seuss | Book |
| Randy Thom | Sound Re-Recording Mixer |
| Randy Thom | Supervising Sound Editor |
| Gary Rizzo | Sound Re-Recording Mixer |
| John Powell | Songs |
| Cinco Paul | Songs |
