As one of the main focus characters of the original two series, his role primarily concerns his friendship with Archie "Snake" Simpson (Stefan Brogren) and Derek "Wheels" Wheeler (Neil Hope), his on-and-off romantic relationship with Caitlin Ryan (Stacie Mistysyn), and in The Next Generation, his relationship with his stepson Craig Manning (Jake Epstein).

Characterized as a class clown and a slacker in the original series, Joey was known for his trademark fedora and Hawaiian shirts and humorous, immature attitude.

However, he shows a more sensitive, caring side when his friends are in a crisis, such as his attempts to comfort Wheels after his parents' death in a vehicular accident.

[3] Towards the end of the year, his school principal announced over the PA system that a production company had dropped off audition forms for a children's television series that was to be filmed over the summer; the flyer specifically read "No Experience Necessary".

[3] Prior to Mastroianni, Billy Parrott auditioned for Joey Jeremiah, but was instead given his own character, Shane McKay.

[6] The season 2 episode "Trust Me" features a plotline based on a real incident involving Mastroianni, in which some of his castmates goaded him into driving a shuttle bus that routinely transported the cast.

[9] In later interviews, Mastroianni revealed he left The Next Generation because of his dissatisfaction with the writing of the returning original characters, including his own.

[10] At the 2022 Toronto Comicon, he elaborated that he had kept quiet for years about his frustration with the writing for Joey and other returning classic characters such as Spike, Caitlin, and Snake.

[11] In addition, he felt that his character had served its purpose in helping pass the torch to the newer generation, and declined an offer from Linda Schuyler to return for the sixth season.

He is characterized as a humorous, extroverted, immature slacker and self-styled ladies man who has a penchant for trying to either charm or coerce his peers into getting or doing what he wants.

In Degrassi High, it is later revealed that he has dysgraphia, a learning disability involving poor handwriting and spelling, which accounts for his academic struggles.

Both Joey and Wheels later became best friends with Snake during the second season, when the trio formed a garage band called The Zit Remedy for the school's talent show.

Their dinner is cut short when Caitlin tries to hint to an oblivious Joey that her parents are out of town and she hates to sleep alone in the house; even running her foot along his leg fails to make her point until she slips a condom into his hand.

Still awash in the afterglow the next day at a cottage retreat attended by their classmates, Caitlin accepts the offer of marriage that Joey had made on her graduation night.

On the day before their combined nine- and ten-year high school reunion, Joey attempts to sell a car to his old friend, Lucy Fernandez who asks if he is coming and hints that his wife would not have wanted him to become a recluse.

The advertisement showed Joey ripping his shirt off, resulting in a blunt critique from Caitlin's new fiancé, Keith.

Toying with her discarded engagement ring from Keith, Caitlin asks Joey if it reminds him of that day eleven years earlier at the beach.

After an emotional moment in front of Julia's grave, where Craig admits to having been abused by Albert, Joey welcomes him into his home and helps him to file a police complaint.