After the events of Ben 10: Ultimate Alien, a sixteen-year old Gwen is seen with Ben and Kevin chasing Zombozo through Bellwood. Shortly after fighting and capturing Zombozo, Gwen says her goodbyes to Ben because she is heading to college since she took honor classes. She then tells Ben to stay out of trouble and gets into the car with Kevin (who also reveals that he will be staying with Gwen, but near campus), then the two drive off, leaving Ben to deal with Zombozo.
In Many Happy Returns, Gwen returns with Kevin to visit for the week. She returns with an all-new look, similar to when she was a kid. They mark their return by saving Ben as Rath from a burning building when he was trying to save a toy. The next day, they go for Smoothies, only to be attacked by Princess Looma Red Wind and Kevin revealing that he was forced to marry her in order to get the engine block he needed for his ship, and later his car. After battling Looma again, Gwen shows her new Anodite form to try to finish it, but Looma's father intruded by re-forcing Kevin to marry her. Ben defeats Looma, but he later finds out it just made him Looma's fiancée. Kevin awkwardly leaves, not telling Ben he just came to Bellwood to "pawn" Looma on him. Gwen assures Ben that she will make frowning faces on the ride back and the two ride off.
In Gwen's new Anodite form, her clothes stay intact but with a different design reminiscent of her Lucky Girl outfit with the addition of a skirt with a belt. She now possesses blue gloves and in place of her glasses is a blue mask. Her shirt is a darker blue with a light stripe (the colors of her regular shirt become inverted), the cat face turns black with pink eyes and the shirt cuts off to reveal her stomach and navel. As for her physical appearance; her skin becomes a bright plum color and her eyes and hair glow a bright pinkish color, with her hair retaining her human half's length.
Gwen returns in Showdown: Part 2 where it is revealed that Grandpa Max used her to track Ben's location through his mana. She also goes along with Azmuth and Rook to the remains of Galvan B to find clues to solve the problem involving reviving the Galvanic Mechamorphs and defeating Malware. Gwen is seen again after Malware is defeated and is surprised that Kevin knows that Khyber's former dog is a girl. Gwen then flies back home along with Ben, Rook, Kevin, and Max.
Gwen is seen again in The Frogs of War: Part 2 where she, along with Rook, Kevin, and Argit are gathering supplies and weapons to fight against the invading Incurseans. However, they nearly get blasted by some Incurseans and escape outside avoiding the Way Bads. They eventually reach Ignacius Baumann's shop and Gwen and the others enter to the back. Gwen breaks up an argument between Rook and Kevin and suggests breaking Grandpa Max out of the Plumber base. As she and the other prepare to do so, they are stopped by Attea and a bunch of Incurseans. However, an alien by the name of Bullfrag fights away the Incurseans and leads them to a ship. Bullfrag gets knocked out by Kevin and gets tied up demanding answer. Gwen then looks into Bullfrag's eyes and tells Blukic to let him go. The group eventually reaches the Plumber base and they free Driba and Grandpa Max and Bullfrag goes up to him saying "Grandpa" revealing to be actually Ben but Attea soon appears behind them. Kevin is surprised and Gwen tells him that who else comes up with a name like "Bullfrag." Gwen then blasts Attea becoming annoyed with the flirting. Gwen then hears the story on how Ben survived in space and unlocked Bullfrag. Gwen is seen again after the capture of Milleous but soon knows that Attea was playing them the entire time. Gwen and the others are forced to watch Attea leaving with the entire Incursean army as if anything hasn't happened. As Ben says that he wants a smoothy if a Way Bad hasn't destroyed all of them, Gwen remarks "Ben Tennyson is back."
Gwen returns from college in Mud Is Thicker Than Water. She visits Ben at the Plumber Headquarters while Rook and Kevin head off to an auto-show, only to find out that her cousin, Lucy Mann, has become a plumber. They realize that their plumber technology has been stolen by a spy. She and Ben then saved the power core from exploding, which was used as a distraction so that the spy can steal their plumber tanks. She suspected that Lucy was the spy as she arrived since the threat started. After which, they decided to move all the plumber tech off the planet, starting from the Anihilaarg, which Blukic and Driba had fixed. Psyphon's Gang then attacks the plumber ship and took the Anihilaarg. Gorvan, was then revealed to be the spy among the plumbers. Suddenly, the plumbers arrive to take on Psyphon and his gang. Psyphon was shocked and he blames Gorvan for telling the plumbers their location, but Lucy, disguised as Liam, revealed herself and she was the one who told them their location, making Psyphon even more angry. Gorvan tries to escape with the Anihilaarg, only to be stopped by Gwen using her judo techniques learned for nine years. Psyphon and his gang is stopped by Ben as Crashhopper. Suddenly, Vilgax arrives, scaring Psyphon, only to be Lucy as Vilgax in disguise. Psyphon was then defeated by Lucy in her Lenopan form and Crashhopper. Gwen throws the Anihilaarg at Ben, only to be revealed it was a fake one to use as bait to stop the threat. Back at the Plumbers Headquarters, Gwen apologizes to Lucy for suspecting her but Lucy did not mind at all, and the two of them started talking in the end.
Gwen, Kevin and Zed are seen in the Rust Bucket 3 in For a Few Brains More. They helped Ben, Rook and Grandpa Max but Gwen failed to save the Proto-TRUK, which ended up being damaged with Grandpa Max and Rook passing out. Khyber attacks Kevin and Zed takes his Panuncian. Gwen helps Rook and Grandpa Max up, with Azmuth removing her spectacles. Albedo as Ultimate Gravattack takes Azmuth's brain from Ben as Gwen traps Khyber using a few planks. Ben transforms into Pesky Dust to get information from Khyber about Albedo's location in his dream. Gwen's shield broke from Khyber's Panuncian and Rook shoots at it. Gwen traps it as Kevin removes the Nemetrix with the help of Ben as Water Hazard. The team head of to Billions Tower to confront Albedo. Gwen shoots mana at Albedo but her attacks got reflected and she was knocked out. The team was then trapped by Albedo's power, Azmuth transforms Ben into Bloxx and frees the team. Albedo transforms into Ultimate Humungousaur and hits Ben. Azmuth transforms Ben into a new alien, Atomix, who easily takes out Ultimate Humungousaur. He hits Gwen and the rest of the team up to high altitudes as he finishes Albedo, who transforms into Ultimate Spidermonkey, with a blast. Azmuth receives his brain back as Albedo turns into his eleven-year old Ben look, altered by Azmuth, the team just watches him.
Gwen makes an appearance in Mystery, Incorporeal, in which Ben and Rook start at Friedkin University. She, Kevin and Zed eventually help Ben to fight a Stone Creature, and to investigate who was behind the attacks of the creatures. Once the team finds that it was Darkstar's doings, Ben, Rook, Kevin, and Zed fight many obstacles, including a fully-powered Morningstar who has absorbed Gwen's powers. The team eventually stops him and saves Gwen with the help of Ben as Ghostfreak. Soon Ben saves the day and Gwen attains her first mystical Charm of Bezel, also providing the ability to telekinetically fly at high speeds. For saving the day, Ben is given an honorary degree and he and Rook leave for Bellwood.
In Charmed, I'm Sure, although Gwen did not make an on-screen appearance, Rook was texting her throughout the episode. Rook mentioned that they talk a lot, and she told him all about Charmcaster. She helped Rook on Ben's poor skin condition, as well as to carry magical supplies such as her spellbook to try and cure Ben's skin and defeat Charmcaster. Ben thinks that Gwen was trying to do something bad, but Rook does not agree to it. However, most of the spells Gwen asked Rook to try did not work as Rook was not in close proximity to the Alpha Rune until the end where Charmcaster held possession of it. In the end, Gwen told him that it was due to Swampfire's growth phase into its new form that caused Ben's poor skin condition.
Gwen makes an appearance in the two-part episode Weapon XI: Part 1 and Weapon XI: Part 2 where she receives a coded message from Kevin. She, along with Rook and Ben then set off to find the Amalgam Kids. Then, together with Argit and Zed, the team sets off to find Kevin and take on the Rooters in the Null Void. Servantis then turns the Amalgam kids and Kevin against Ben, forcing Gwen, Rook, Ben and Zed to take them on. Gwen and Rook then take on Swift and Leander who are defending the Null Void Projector after escaping from the Mutant To'kustars while Ben goes into the Rooter's Headquarters to take on Kevin, who absorbs his Omnitrix and mutates for the fifth time. Gwen was knocked out by Swift and was hurt. Fortunately, Rook immediately saves her from the exploding generator of the Null Void Projector which Swift and Leander attacked at. Gwen then wonders how they would get out while Ben, as Swampfire is still struggling with Kevin's attacks, eventually passing out. Kevin then surprises Servantis and shocks the Amalgam kids by knocking out his loyalty neuro-matrix and is locked out of their heads for good. Gwen, Rook and Zed arrives and were glad Kevin did not turn insane, thanks to the first brain spark from Servantis. The Plumbers then arrive with the Magistrata, having the Rooter's plumber status revoked and the Plumber tech confiscated, leaving them stranded in the Null Void with the Mutant To'kustars. Gwen is then seen talking to Kevin about the letter containing his coded message as Ben is eager to eat, wishing The Rooters luck when facing the Way Bads.
Gwen makes an appearance in Charm School, where she was attending class conducted by her favorite teacher Hex. They have got over their conflicts as Hex has put his past behind him and is a professor in her school. She was surprised to notice Charmcaster in her school, so she decided to talk to her. Later, she called Ben and Rook over to her school on the case. Ben attacked Hex but Gwen later explained to him that Hex is a good guy now, proven by using her magic spell that confirms that all the students did not get any influence or brainwashed by Hex, that he was completely normal. She then faces Charmcaster, who has turned Hex into a Stone totem and obtained his staff. As Lucky Girl, Gwen gave everything she got in the face off with Charmcaster, but none of her spells and attacks work on her. She then casted a spell which she can form clones of herself, as a distraction so that she could grab Hex's stone totem. Together with Ben, as Ghostfreak, Kevin, Rook and Zed, they led Charmcaster into Hex's library in the school as Gwen had a plan in mind. When Charmcaster reached the library, Gwen blasted her and Charmcaster assumes she was about to give up. But because Gwen was holding onto Hex's stone totem, it gives her access to his library and all the magical powers, making her even more powerful. This time, Charmcaster's attacks do not work on her as Gwen grabs Hex's staff. As Charmcaster was about to make another attack, she quickly opened a portal to Ledgerdomain and sent both Charmcaster and Hex into that dimension. Gwen now holds possession of her favorite teacher's library of magical artifacts and his staff, leaving her with a huge responsibility to take care off, as well as having a lair for her Lucky Girl in campus. The episode ends with Kevin and Rook going off to the auto-show with an excuse, and Ben left in school, who is trying to figure out on how to get back to Bellwood.
In Third Time's a Charm, Gwen is lured to Ledgerdomain when trying to get Kevin's car back. Charmcaster appears and transforms Gwen into a stone totem, which she puts into her bag. There, Gwen encounters Hex, Darkstar and Adwaita, who are too busy bickering with one another to help her escape. Gwen comes up with her own plan, drawing a magic circle on the inner bottom of the bag and tricking Charmcaster into reaching in and touching it. When she does, Charmcaster is transformed into a totem and all her victims restored to normal. The episode with Gwen keeping Charmcaster, who is sealed in her own bag, in her headquarters, remarking that she believes she and Charmcaster can become friends now that Charmcaster has been rendered harmless.
Gwen briefly appeared in The Most Dangerous Game Show where she is among the contestants to compete for Ben's hand in marriage. However, she was quickly eliminated before the competition started after Ben told Zenith that they were cousins, along with other family members who are already related to him.
At the end of A New Dawn, after watching the universe created, Ben called Gwen to get Kevin as he proposes that Ben, Gwen, Rook and Kevin go on a road trip together to explore the universe that they watched being created.