In secrecy, however, Mr. Frederickson is Boss Awesome—a superhero that is widely regarded to be the greatest of all time. Boss Awesome's history traces back to the 1970s, in during which he regularly saved San Fransokyo from the clutches of his arch-nemesis, Baron Von Steamer. In present day, Mr. Frederickson has retired the Boss Awesome mantle, but remains the adventurous humanitarian he was in his youth. As such, he is rarely home in San Fransokyo and instead spends much of his time globe-trotting. He also keeps tabs on all known criminals, offenders and villains that lurk throughout San Fransokyo, even those of modern day such as Momakase and High Voltage.
Mr. Frederickson's superhero alter-ego was kept a secret from Fred for most of the latter's life. When Fred finally learns the truth, Frederickson shows excitement in passing his stories down to his son.
According to Fred, Mr. Frederickson gave him the family mansion while he and Mrs. Frederickson were away on a vacation to the family isles. In the post-credits, Fred discovers a secret lair behind a painting of his family. Mr. Frederikson then appears to his son's amazement and reveals how he has once lived a double life as a superhero. Out of joy and relief of reuniting with him, Fred hugs his father, who hugs him back and tells him that they have a lot to talk about to each other.
Mr. Frederickson is a minor character in the series, making guest appearances. Big Hero 6 will sometimes visit his secret lair to find a way to eliminate a new foe.
He first appeared in the episode "Fred's Bro-Tillion". During a trip out of town to deal with an avalanche on the family mountain, Fred is pursued by his father's longtime adversary, Baron Von Steamer, who sought to exact revenge against Frederickson by eliminating his only son, only to kidnap Wasabi by mistake. Frederickson is contacted by Big Hero 6 about the ordeal via his secret headquarters in his mansion. While offhandedly knocking out a yeti, he tells them how to find the locations of Steam's known hideouts.
In "Kentucky Kaiju", Frederickson appears on Fred's TV, expecting to speak with his son only to find Hiro instead. While offhandedly battling mummies, he takes note of the Nanovex weave Hiro was using to give himself super strength. Frederickson reminisced about attempting the same thing when he was a rookie hero too before eventually realizing his true strength was his can-do attitude as well as his wealth. He then advised Hiro to leave the premise, as he didn't recognize him at first, so he alerted security.
In "Steamer's Revenge", a statue of Boss Awesome is erected in the San Fransokyo bay by an anonymous source. Meanwhile, Steamer sends a message to Boss Awesome, demanding they meet in Night Market Square. Because Mr. Frederickson is on the other side of the world saving sloths at the family rainforest preserve, Fred is chosen to disguise himself as Steamer and trick the villain into revealing his plans thus allowing Big Hero 6 to defeat him. Mr. Frederickson try to train Fred through video chat, but the latter's skills are lacking greatly. Fred nevertheless confronts Steamer as according to plan, and, despite Steamer having learned from his past defeats, surprisingly succeeds in his task. When Steamer tries to escape, Fred uses one of Boss Awesome's signature moves to detain him.
In "The Fate of the Roommates", Fred calls his father for advice on how best Heathcliff could infiltrate Mr. Sparkles and Yama's Maximum Insane Driving Challenge. Mr. Frederickson remarked that he always disliked fighting "screwball villains", but assures everyone that Heathcliff is a master of disguise and deception.
In "Supersonic Sue", Mr. Frederickson is at the family ranch have a "tussle" with a bull named Benjamin, when Big Hero 6 calls him, asking for information on another of his enemies, Supersonic Sue. While casually ignoring Benjamin's attempts to knock him down, he recalls how Sue used to be a roller derby queen until she was banned from the sport for using performance enhancing rocket skates and became an inspiration for female villains. Sadly, he had no clue on how to locate her, as he doesn't stay in touch with old foes, so the team decide to pay a visit to Baron von Steamer.
Mr. Frederickson later discover that the team left the video chat open and overhears them debating whether to rescue Steamer, who had been abducted by Supersonic Sue. He asserted that a real hero helps everyone, even their own foes. Fred thanks him for the advice before alerting him to Benjamin about to attack from behind.
Later, when Sue and Steamer team up to defeat Big Hero 6 to lure Boss Awesome into a trap, Mr. Frederickson decided to come out of retirement to face his old foes. Despite his combat skills being a bit rusty, he manages to hold his own until Sue overpowered him. But she then made the mistake of declaring herself Boss Awesome's true archnemesis, prompting Steamer to turn on her, allowing Boss Awesome to defeat him. As the two villains were being taken into custody, Steamer asked Boss Awesome to settle for them who his true archenemy was. Boss Awesome answered that it was cabbage soup, causing Steamer to cry out in anguish.
- Since the release of 20th Century Fox's X-Men in 2000, Lee had traditionally made cameo appearances in films based on Marvel Comics properties. Big Hero 6 marked his 22nd appearance in a Marvel-based film, as well as his 2nd appearance in a Disney-branded film (the first one was The Princess Diaries 2: Royal Engagement).
- Him being a superhero is a reference to Lee's past role as the Mayor of Super Hero City in The Super Hero Squad, where he fancied himself a superhero. It could also be a reference to his role as the voice of the future version of Tony Stark in Avengers Assemble.
- Mr. Frederickson claims that cabbage soup is his arch-enemy because he loves it, but "it doesn't love [him] back."