Season 1 (2004)

Production codes are from the file names of the episodes on peepandthebigwideworld.com

Season 2 (2005-2006)

Production codes are from the file names of the episodes on peepandthebigwideworld.com

Season 3 (2007)

Production codes are from the file names of the episodes on peepandthebigwideworld.com

Season 4 (2010)

Production codes are from the file names of the episodes on peepandthebigwideworld.com

Season 5 (2011)

Production codes are from the file names of the episodes on peepandthebigwideworld.com

Main

• Peep (Voiced by Scott Beaudin^[7] in the first 3 seasons, Shawn Molko in Season 4 and Maxwell Uretsky in Season 5): A male, yellow chicken who is very curious. He is the youngest bird of the group. The show's title is derived from his name. Peep is female in the original short film.
• Chirp (Voiced by Amanda Soha): A female, red robin who is also curious, and attempts frequently to fly, with unsatisfying results, until "A Daring Duck", when she flies from the ground. In "Big Bird" she meets a real robin for the first time. She is Peep and Quack's friend. Chirp is male in the original short film.
• Quack (Voiced by Jamie Watson): A male, blue-purple duckling who wears a white sailor's hat. He is older than Peep and Chirp, as they are still chicks. He frequently boasts about himself and ducks as a whole, and unwittingly makes many discoveries. Quack is purple in the original short film and is now referred to as blue, but is still quite indigo. He also seems to have a hoarding issue, as evidenced in the episode "An Inconvenient Tooth, Part 1."
• The Narrator (Voiced by Joan Cusack): The Narrator tells the episode's story, although the characters rarely have any interaction with her. In the episodes "Dry Duck, Part 1" the birds did have a short interaction with her and in "Quack Quiets the Universe" she and Quack interact as well.

Minor

• Ant (Voiced by Robert Tinkler): A busy male ant who appears in some episodes.
• Beaver Boy (Voiced by Tessa Marshall): A young naïve male beaver who lives in an adjoining pond to Quack's. He appears in several episodes. His desire to please his mom and dad often results in him chewing down too many trees. He often calls Quack "Blue Sailor" Peep "Yellow Guy" and Chirp "Red Round".
• Beaver Mom: (Voiced by Debra McGrath) Beaver Boy's workaholic mother.
• Beaver Dad (Voiced by Phillip Williams): Beaver Boy's businesslike father.
• Dragonfly (Voiced by Catherine Disher): A quiet dragonfly.
• Fish: Cohabitants of Quack's pond.
• Frog: A frog who lives in Quack’s pond. He rarely talks.
• Hoot (Voiced by Corinne Conley): A menacing, but kind purple female owl who lives in the Deep Dark Woods.
• Nellie (Voiced by Marium Carvell): A red female dog who acts as a seemingly maternal figure for the birds.
• Newton (Voiced by Colin Fox): An old, male, dark-green turtle who lives under an apple tree.
• Quack #2 (Voiced by Megan Mullally): An annoying pink female duck who has her own pond, built by Quack, Peep, Chirp, Beaver Boy and his parents.
• Rabbit (Voiced by Jayne Eastwood): An excitable and somewhat distracted rabbit.
• Robin (Voiced by Holly Hunter): An adult robin.
• Skunk (Voiced by Adrian Truss): A rather deadpan skunk who lives near Quack's pond.
• Bat (Voiced by Ron Rubin): A shy bat.
• Squeak (Voiced by Kathleen Laskey): An anxious pink, female mouse who lives under a brick and always worries about what could go wrong.
• Tom (Voiced by Alex Hood and Matthew Knight): A sly, male blue kitten with black stripes who often tries to eat Peep, Chirp, and Quack. He is the sole antagonist.
• Raccoon (Voiced by Jeff Lumby): A gobbo, male brown & black raccoon who often tries to wear his sun glasses in "A Peep of a Different Color"
• Blue Jays (Voiced by David Hudson): Silly blue and white birds who love to cause trouble when they see stuff.

United States

Peep and the Big Wide World was originally broadcast on TLC and Discovery Kids — the latter as part of the Ready Set Learn preschool block —, from April 12, 2004 to September 14, 2007. Reruns of the first three seasons continued to air until October 8, 2010 when Discovery Kids discontinued the block to make way for the new network to launch known as The Hub on October 10.

The last two seasons were broadcast exclusively on select local public television stations with episodes distributed by APT from January 4, 2010^[9] to October 14, 2011, though second-runs of previous episodes began as early as April 1, 2007.^[10] APT continued distributing reruns through December 2017, well after commercial networks dropped the program. A total of 60 episodes (120 segments) were broadcast.

On January 1, 2018, reruns of Peep and the Big Wide World began airing on the 24-hour PBS Kids channel, marking the first time the series aired nationally on PBS Kids. Despite being a production of PBS station WGBH, Peep and the Big Wide World was turned down by PBS in 2003 in favor of developing programming directed at "slightly older children".^[11] (The series was geared toward preschool children ages 3–5; meanwhile, PBS eventually launched the PBS Kids Go! block in 2004 which was intended for children above the preschool level.) The broadcast of the series ended on December 26, 2021, when it was replaced with reruns of Dinosaur Train to the 7:30 a.m. weekend morning timeslot.^[12]

APT and PBS Kids broadcasts of Peep and the Big Wide World were paired with a short episode from Pocoyo which aired immediately after each show from 2010 to 2021.

Home video

WGBH Boston Video released the episodes of the first season on DVD in 2005. The 2005 DVD releases each contained six segments of the specified subject; Peep Explores, Peep Finds, Peep Floats, Peep's New Friends, Chirp Flies, and Quack Knows It All. The 2007 DVD release, Peep Figures It Out contained six segments as usual, plus two bonus segments. In 2011, PBS Kids Video released two DVDs; Seasons of Adventure, and Star Light, Star Bright, which contains episodes from seasons two and three respectively. In 2012, PBS Kids Video released two more DVDs; Finders Keepers and Bringing Spring. In 2014, PBS Kids Video released two more DVDs; Diva Duck, and Peep Discovers (which was once available as a limited release to retail stores). As of 2020, all of these DVDs are now out of print and very hard to find, but commonly found at public libraries. In Canada, Entertainment One released three DVDs in both English and French languages; Stick With Me, Peep's Moon Mission, and Flower Shower.

PBS LearningMedia shorts

In 2017, WGBH released PEEP and the Big Wide World: Weather Factors, a media gallery in PBS LearningMedia's Bringing the Universe to America's Classrooms project. Weather Factors contains 4 animated shorts: PEEP and the TOO Windy Day, PEEP and the Chilly Dam, PEEP and the Changing Sky, and PEEP and the Rainy, Snowy Day.^[13]