Tyltyl (teel-teel), a woodcutter’s son. Dressed in a light-blue jacket, scarlet knickerbockers, and white knee-length socks, he is innocent and naïve. At the beginning of the play, which takes place during the Christmas season, he notices the abundance of gifts and cakes enjoyed by his rich neighbors. Accepting his situation without rancor and jealousy, he participates vicariously in their pleasures. The Fairy Bérylune appears at night and asks him to seek the Blue Bird needed to cure her ill daughter. Adventurous and courageous, he finds the Fairy interesting and stimulating, and he answers her questions on her grotesque appearance forthrightly and accurately. His good nature prompts him to seek the Blue Bird, and the Fairy arms him with a magic diamond that enables him to defeat possible adversaries. Along with his sister Mytyl, his dog, his cat, and everyday commodities that are anthropomorphized (for example, Bread, Sugar, Fire, Water, and Milk), he undertakes a journey leading to four successive realms. Although he becomes afraid during his encounter with the Oak and the other elements of nature seeking revenge for past human wrongs, he finds the strength and courage to endure pain and to keep his promise to the Fairy. He encourages Mytyl to share the dangers and difficulties of the quest. At the end, he returns to the security of his home. He is realistic and acknowledges his failure to capture the Blue Bird; however, he generously relinquishes his own blue bird to Madame Berlingot, who, in turn, gives it to her daughter. Cured, the neighbor’s daughter finds momentary happiness. Just as the Blue Bird eludes capture, however, Tyltyl’s bird escapes. Resigned to the situation, Tyltyl recognizes the continual need to seek the bird. By pursuing the quest of happiness, he is prepared again to undertake a voyage to a deeper understanding of life.

Mytyl (mee-teel), Tyltyl’s sister. Appearing in a Red Riding Hood costume, she resembles her brother in innocence and purity. She loves her family and expresses joy in being reunited with her deceased grandparents, brothers, and sisters. In undertaking the journey to capture the Blue Bird, however, she lacks Tyltyl’s resolve and fortitude. During her encounter with Night, she gives in to anxieties, crying and complaining as Tyltyl is about to open the door to the Forest. In contending with nature’s elements, she emits horrifying screams, and unlike her brother, she appears more human than heroic. The search for the Blue Bird reflects a growth of self-understanding and wisdom: She distinguishes the differences of character between the dog and the cat and, like her brother, discovers the secrets of life, the significance of duty and sacrifice, and the elusive and transitory nature of happiness.

Tylette, the duplicitous cat, stands in contrast to Tylo's loyalty. Her character is marked by cunning and independence, as she seeks to sabotage the children's quest to preserve the newfound powers the magical journey bestows upon her and others:

Listen to me! . . . All of us here present, Animals, Things and Elements, possess a soul which man does not yet know. That is why we retain a remnant of independence; but, if he finds the Blue Bird, he will know all, he will see all and we shall be completely at his mercy. . . . This is what I have just learned from my old friend, Night, who is also the guardian of the mysteries of Life. . . . It is to our interest, therefore, at all costs to prevent the finding of that bird, even if we have to go...

Tylo, the anthropomorphized bulldog, remains a steadfast ally to the children during their quest. His loyalty is unwavering, characterized by humorous devotion and an eagerness to protect them:

I want to go with the little god! . . . I want to talk to him all the time!

Facing an assault by the forest animals, Tylo heroically breaks the bonds imposed by his peers, rushing to defend his "little god":

Here! Here, my little god! . . . Don't be afraid! Have at them! . . . I know how to use my teeth! . . . Here, there's one for you, Bear, in your fat hams! . . . Now then, who wants some more? . . . Here, that's for the Pig and that's for the Horse and that's for the Bull's tail! . . . There, I've torn the Beech's trousers and the Oak's petticoat! . . . The Fir-tree's making tracks! . . . Whew, it's warm work!

Tylo's actions consistently demonstrate his dedication and affection for his masters, embodying loyalty and bravery.

Bérylune (bay-ree-lewn), a fairy who appears at the end of the play as Madame Berlingot (behr-ling-oh), the woodcutter’s neighbor. Initially, she enters crippled and grotesque, walking with a cane and appearing with a conjoining nose and chin. She asks Tyltyl and Mytyl to capture the Blue Bird needed for the recovery of her daughter. She gives them a magic diamond that provides them with a supernatural force to ensure their safety. To convince them to undertake the quest, she uses the enchanted jewel to undergo a self-transformation from a hag to a beautiful princess, then to instill life into the furniture and other inanimate objects. At the conclusion, she reappears as the neighbor, accompanied by her beautiful young daughter, who is lame. Tyltyl’s bird brings about a miraculous cure, which, in turn, induces gratitude from Madame Berlingot.

Light, serving as the Fairy's assistant, guides Tyltyl and Mytyl on their quest, illuminating the path to understanding life's profound secrets and the essence of happiness. Her presence underscores the importance of insight and enlightenment in the children's journey, acting as a beacon of hope and wisdom.