Big Bird was designed by a drawing from Jim Henson and built by Kermit Love in 1969. The design was based on a previous Henson creation, a seven-foot-tall (210 cm) dragon that the puppeteer created for a La Choy advertising campaign. The Big Bird performer is completely enclosed within the costume, and extends his right hand over his head to operate the head and neck of the puppet. The Muppeteer's left hand serves as the Bird's left wing, while the right wing is stuffed and hangs loosely from a fishing line that runs through a loop under the neck and attaches to the wrist of the left hand. The right hand thus does the opposite of the left hand: as the left hand goes down, the right hand is pulled up by the fishing line. A secondary muppeteer would be used in scenes where Big Bird uses both his wings or holds something in the right wing.

Big Bird's body suit weighs ten pounds, and his head weighs four pounds. According to writer Louise Gikow, the heat inside the suit is "unbearable, and it's extraordinarily difficult to hold Big Bird's head."

Different versions of Big Bird are portrayed in some international versions of Sesame Street. For example, the Dutch version has a blue bird named Pino. In the Latin American version (Plaza Sésamo), Big Bird's parrot cousin, Abelardo Montoya, is featured. He appears similar to Big Bird, but he is green.

Big Bird's appearance has changed over the years, as has his personality. He originally had very few feathers on top of his head; his body feathers were also more shaggy and unkempt, and his body was not as rounded and full as it is now. His personality was more dopey and "bird-brained" than it later became. He gradually got more feathers on top, giving his head a more rounded appearance, and developed a blaze-like crest of lighter yellow feathers above his eyes. His body got fluffier, rounder and more well groomed as well. His personality developed over time from being a dim, slow-witted character into the childlike innocence he is known for today. Although all the Sesame Street Muppet characters are technically ageless, Big Bird is psychologically written to represent a six-year-old.

The costume is partially assembled by company American Plume & Fancy Feather, using the tail feathers from turkeys; as the feathers are rarely clean, company owner Anthony Trento calls the Big Bird costume his "toughest customer". Sesame Workshop is said to reject roughly 90 percent of all the feathers selected for use on the costume.

• Sesame Street (1969–present) (TV)
• Christmas Eve on Sesame Street (1978) (TV)
• A Special Sesame Street Christmas (1978) (TV)
• The Muppet Show ... episode #318 (1979) (TV, Crossover with The Muppets)
• The Muppet Movie (1979) (Crossover with The Muppets)
• Big Bird in China (1983) (TV)
• Don't Eat the Pictures (1983) (TV)
• Sesame Street Presents: Follow That Bird (1985)
• Sesame Street: Play-Along Games and Songs (1986)
• The Muppets: A Celebration of 30 Years (1986) (TV, Crossover with The Muppets)
• A Muppet Family Christmas (1987) (TV, Crossover with The Muppets)
• Sesame Street: Magic on Sesame Street (1988)
• Count It Higher: Great Music Videos From Sesame Street (1988)
• Big Bird in Japan (1989) (TV)
• The Muppets Celebrate Jim Henson (1990) (TV, Crossover with The Muppets)
• Big Bird's Birthday or Let Me Eat Cake (1991) (TV)
• Sesame Street Stays Up Late (1993) (TV)
• Sesame Street: Big Bird Sings! (1995)
• Elmo Saves Christmas (1996) (TV)
• Sesame Street: Get Up and Dance (1997)
• Sesame Street: Kids' Favorite Songs (1999)
• The Adventures of Elmo in Grouchland (1999)
• Sesame Street: Let's Make Music (2000)
• Elmo's Musical Adventure: The Story of Peter and the Wolf (2001)
• Sesame Beginnings (2006–2007)
• The Furchester Hotel ... episodes #201 and #216 (2016) (TV)
• The Magical Wand Chase (2017) (TV)
• Sesame Street: Elmo's Playdate (2020) (TV)
• The ABCs of COVID-19: A CNN/Sesame Street Town Hall for Kids and Parents (2020) (TV)
• Furry Friends Forever: Elmo Gets a Puppy (2021) (TV)

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The book “G” is for Growing: Thirty Years of Research on Children and Sesame Street cites a producer of Sesame Street who refers to Big Bird as a canary. In the series 11 episode, "Mister Rogers Talks about Competition" of the show, Mister Rogers' Neighborhood, Big Bird was asked by King Friday XIII if he was related to the cassowary; he replied, "I'm actually a Golden Condor." On the January 23, 1976 episode of Hollywood Squares, Big Bird was asked what kind of bird he is and said he was a lark, causing host Peter Marshall to crack up. In the film Don't Eat the Pictures, Osiris calls Big Bird an ibis. Zoologist Mike Dickison suggested in his popular Pechakucha talk that Big Bird represents a unique species that evolved from the whooping crane. For decades, Oscar the Grouch has been calling Big Bird a turkey, more as an insult rather than a reference to his species. Big Bird is always described as being flightless.