The character designs in both the picture book series and television series are meant to represent and reflects on the character's personality and overall characteristics (e.g. Catboy/Connor's design representing a cat, and Owlette/Amaya's design representing an owl).
While on the other hand, the character designs also take inspiration from other existing characters outside the television series and book series such as funny cartoon characters, superheroes from DC Comics and Marvel Comics, and mythologic and folkloric characters from mythologies and folklores.
In the PJ Masks television series, the younger male and female characters typically wear 50s vintage clothing fashion style of teenagers combined with aesthetics of modern clothing style. Optionally, characters such as the PJ Masks wear outfits that reflect on the representation of their superhero identities such as having colors that match their superhero costume colors. Examples include:
This is not always the case, as adult characters are shown to be the only exception as they are shown to wear contemporary clothing fashion style.
The character and Super Costume designs for superheroes in the PJ Masks television series take the inspiration from Marvel Comics superheroes such as Spider-Man, Doctor Strange and Captain Marvel. The appearance of their costumes take the combination of pajamas and superhero costumes with a theme associated with animals, nighttime or nature.
The Super Costumes often have superhero accessories and gadgetry such as having an amulet symbol to mark their identity, gloves, boots, textured sections on costumes, glowing patterns, forearm gauntlets, shields, lightning patterns, armored helmets, domino masks, half face masks, full head masks, or highlights and paddings on foot, elbow, shoulder and hand sections. However, the only superhero accessories and gadgetry that is excluded are speedos and belts.
In some cases, Super Costumes will lack some superhero accessories, such as costumes intended to solely look more like pajamas rather than a combination with pajamas and proper superhero costumes. Instances include animal-themed costumes to look like actual animals while removing accessories and gadgetry that doesn't fit the exact physical characteristics and actual abilities of an animal, such as Yoyo having natural pattern stripes compared to Catboy's lightning pattern stripes, Gluglu lacking Gekko's shoulder paddings and his Super Gekko Shield ability, and costumes lacking amulet symbols, accents and foot highlights.
Energuman is shown to be the only exception as his costume design is intended to not look like a combination of slightly altered pajamas and real superhero costumes, but it is made to look like a full-on typical superhero costume bearing the closest similarity to the DC Comics superhero, Batman, than the rest of the other characters of the picture book series.
The character and costume designs for the supervillains in the PJ Masks television series take the inspiration from Marvel Comics superheroes such as Black Cat, Green Goblin, Doctor Octopus and much more. Like comic book supervillains, their costume designs often have dark and ominous colors (e.g. black, purple, turquoise, teal, dark blue, grey etc.) to reflect on their status as a villain.
In the Pyjamasques book series, the designs for the villains greatly vary from anthropomorphic monsters, folkloric characters and much more with casual looks and appearances. However, some of the characters are shown to be partial exceptions such as Roméo, Sorceline and Ninjaka as they are the fewer characters to resemble actual supervillains from Marvel Comics, except they are been given some casual accessories and looks to their costume and character designs to match the atmosphere and theme of the Book Continuity in comparison to their television counterparts (Romeo, Luna Girl and Night Ninja).