After being forced to move his Money Bin to a location farther away from his mansion, Scrooge McDuck requested Gyro to build a robot who could guard the Bin from robbers. After Gyro's first attempt, the GICU-2 proved to be too efficient at preventing anyone, including Scrooge, from getting close to the Money Bin, Scrooge ordered Gyro to build a new security guard that would have a brain. Gyro proceeded to build a cybernetic suit that would be "bulletproof, fireproof, and knuckleproof." However, due to Scrooge saying that he wanted a security guard with a brain, they would need to hire a person to wear the suit. And to prevent the suit from falling into the wrong hands, Gyro programmed it to be activated by use of a secret code word that he figured nobody but the wearer would ever use - "blatherskite."
As fate would have it, Scrooge's new accountant, Fenton Crackshell was at the moment having trouble trying to retrieve Scrooge's Number One Dime after it was stolen by the Beagle Boys. Upon overhearing Scrooge and Gyro talking about it, Fenton decided to borrow the Gizmosuit and use it against the Beagles. In his attempt to put the suit on, Fenton uttered his catch phrase, "Blatherin' blatherskite," unaware of the second word being the trigger word for the suit, and officially became Gizmoduck for the first time. From then on, Fenton always uses "blatherin' blatherskite" to become Gizmoduck, despite only needing the second word; it is possible that he does not realize he doesn't have to say the entire phrase.
Once the Gizmosuit has been donned, the only way to extricate oneself from it is to intercept the electronic signal sent to a television by a television remote control. Fenton discovers this while standing in front of his mother's television, after having previously been made to sleep in the carport.
Aside from Fenton, several other DuckTales characters have also worn the Gizmosuit at least once. In the third part of "Super DuckTales", Fenton's mother accidentally ended up wearing the suit when she shouted her son's catch phrase after he accidentally destroyed her TV. She would wear the suit again in "The Duck Who Knew Too Much." Launchpad McQuack has also worn the Gizmosuit at least twice, in the episode "A Case of Mistaken Secret Identity" and the Disney Adventures comic story "A Switch in Time" (in which Scrooge had Fenton and Launchpad switch jobs). Additionally, in "New Gizmo-Kids on the Block," Mrs. Crackshell accidentally shrank the Gizmosuit, which also somehow resulted in the code word being shortened to "blah." Due to this, Huey, Dewey, Louie, and Webby all ended up wearing the suit over the course of the episode.
When Gizmoduck appeared on Darkwing Duck, the Gizmosuit had a noticeably altered design; it was somewhat smaller and lacked the black coloring in the upper arms. This may be because, in the DuckTales episode "Attack of the Metal Mites," the suit was eaten by Flintheart Glomgold's Metal Mites, and thus it was slightly redesigned when it was repaired.
In "The Legend of the Chaos God", when Solego attempted to possess Fenton, he called for the Gizmosuit, only for Solego to take control of the suit himself. Solego used the Gizmosuit to get himself to St. Canard and merge his medallion back with its gold setting, releasing him from the medallion. In the chaos that followed, Fenton regained control of the Gizmosuit, but it was then blown up by Solego. Fortunately, once Darkwing Duck defeated Solego, the Gizmosuit was restored back to normal.
In the 2010 Darkwing Duck comic book's first arc, "The Duck Knight Returns", it was revealed that Taurus Bulba tried to take control of the Gizmosuit (which had been left at Gyro's because at this point, Fenton was missing for reasons that will likely be canonically explained in the Joe Books continuation), but since he had become a machine himself, the Gizmosuit did not register Bulba as a person. Bulba planned to find a lackey and make them wear the Gizmosuit until he could access it himself, but to avoid chances of that happening, Gyro changed the secret code word. However, the new code word he chose turned out to be Gosalyn Mallard's catch phrase, "Keen gear," and thus, when she said the phrase near the suit, she took control of it, becoming Gosmoduck. Darkwing, Launchpad, and Gosalyn agreed that she would hold on to the Gizmosuit, but she would only use it in case of an emergency. However, in the comic's second arc, "Crisis on Infinite Darkwings," the Gizmosuit was destroyed during Darkwing, Gosalyn, and Morgana McCawber's battle against Negaduck and Magica De Spell.
In the comic's final arc, the "Dangerous Currency" crossover story, Gosalyn returned the broken Gizmosuit to Scrooge, and he had Gyro and Honker Muddlefoot repair it. Due to Fenton being captured at this point, they also modified the suit so that it would send out a signal and retrieve Fenton from his whereabouts. Unfortunately, the suit was then stolen by Megavolt and the Beagle Boys and brought to the Phantom Blot's hideout where Fenton was being held captive. The villains then had Gizmoduck transformed into a monster by the slime, but he was fortunately reverted back to his normal form by his mother yelling at him and was able to escape. However, "Dangerous Currency" was retconned as being non-canon (and as such was not reprinted in Darkwing Duck: The Definitively Dangerous Edition).
Canonically, the comic's continuation under Joe Books shows Gizmoduck wearing a new, slightly-redesigned Gizmosuit, the most notable difference being that the stylized "R" emblem on the chest plate now resembles a "G", plus the addition of a jet-pack. At the time of this writing, however, little else is known about the new Gizmosuit.
In the video game DuckTales Remastered, the Gizmosuit is taken apart when Fenton gets kidnapped by the aliens on the Moon level. To progress through the level, Scrooge has to travel through the aliens' spacecraft to find the parts of the Gizmosuit.