Junior Knight is a fictional character from the BBC soap opera EastEnders, played by Micah Balfour. Junior was introduced by executive producer Chris Clenshaw in episode 6906, broadcast on 13 May 2024, as the estranged son of established character George Knight (Colin Salmon), and half-brother of Gina Knight (Francesca Henry) and Anna Knight (Molly Rainford). His introduction billed him as a "sleazy, secretive businessman". Outside of Junior's lengthy, complicated history with his father, his storylines have prominently followed his serial cheating on his wife Monique Knight (Busayo Ige), his affair with his former stepmother Cindy Beale (Michelle Collins), the reveal of their affair, and becoming a suspect in Cindy's subsequent attack.

After being referenced on-screen by his family on several occasions, Junior's arrival was announced on 2 May 2024, with Emmerdale actor Micah Balfour being cast in the role. It was confirmed that the actor had already begun filming prior to the announcement. The character was announced as the estranged son of established character George Knight (Colin Salmon). Speaking on his casting, Balfour stated he was "thrilled" to join the soap, having grown up as a fan, and described walking onto the set as "surreal". Junior's reasoning for his estrangement and his upcoming arrival was initially left ambiguous, but his relationship with his father was described as "fraught" and long-running. Outside of their strained relationship, very little had been revealed about Junior prior to his introduction. The character was "set to cause some trouble" for the residents of the show's setting, Walford. Executive producer Chris Clenshaw teased: "Junior arrives in Walford following an unlikely meet with his dad and is quickly thrust into the heart of the drama. However, it will soon become apparent to viewers that there is more to Junior than meets the eye". Balfour echoed such; "Junior is an exciting character to play as he's a complex man, and he's going to cause a bit of a stir".

Junior's arrival was teased to be an "explosive reunion" for George, whom had been on a path of self-destruction leading up to his son's arrival, with George's daughter Anna Knight (Molly Rainford) being the one to contact Junior. Junior was deemed "a major new face" and further teasers revealed he would have a one night stand with Bianca Jackson (Patsy Palmer) early into his stint. The character made his first appearance in episode 6906, broadcast on 13 May 2024. Junior's introduction portrayed him as a cheater, as it was revealed that he was married to Monique Knight (Busayo Ige) with a child, Xavier Knight (Chase Dean-Williams), after he experienced a "difficult reunion" with George and slept with Bianca, unbeknownst to the entire Knight family. It was later announced that Monique and Xavier would briefly join the show as part of Junior's initial development. Once his night with Bianca is revealed, Monique leaves him and takes Xavier, as it transpires that he had been unfaithful to her multiple times before.

After witnessing George have an intimate moment his ex-wife Cindy Beale (Michelle Collins), despite being engaged to Elaine Peacock (Harriet Thorpe), Junior confronted Cindy before sharing a kiss with her, Despite Cindy being his former stepmother, the two started an affair, with Cindy cheating behind the back of her husband, Ian Beale (Adam Woodyatt). In July 2024, it was announced that their affair would risk exposure. In a Radio Times interview, Balfour said Junior was "excited" by the affair, and that Junior's attraction to Cindy was rooted in her marriage to Ian making her "unattainable" and how "he's always at arm's length" from her as a result. The actor added that Junior enjoyed being deceitful: "He likes the clandestine nature of their relationship and enjoys the thrill of potentially being caught doing something he's not meant to be doing." Acknowledging Junior's recent decision to offer Cindy's son Peter Beale (Thomas Law) a job, Balfour explained that Junior was aware that Cindy's behaviour was becoming suspicious to her loved ones, so attempted to pacify Peter by ensuring he wasn't around Cindy as often. He added that this had the added benefit of Junior being able to keep Peter busy, preventing Peter from discovering the affair. The actor added that when Junior offered Peter the job, he knew Cindy wouldn't be happy. Balfour noted that Junior enjoyed "winding Cindy up and keeping her on her toes", so didn't care when Cindy asked Junior to rescind the job offer to Peter.

Balfour explained that Junior enjoyed his "fiery and passionate" interactions with Cindy. When asked if Junior had any reservations about sleeping with his former stepmother, Balfour responded that Junior's original decision to do so was only out of resentment for George as a way to spite him, but since then Junior had developed genuine feelings for Cindy, and that Junior did not care about how it would affect his family as Junior believes "what people don't know can't hurt them". Balfour predicted that the affair would worsen Junior's relationship with George. The affair continued in secret until it was announced on 25 November 2024 that the affair would be revealed during the show's upcoming Christmas episodes. The affair was teased to be "spectacularly exposed" and the fallout was set to depict that "all hell will break loose among the Beale and Knight families".

The affair was unveiled to a crowded The Queen Victoria pub in episode 7037 by Lauren Branning (Jacqueline Jossa), who did so as a way of getting revenge on Cindy for getting Lauren addicted to painkillers while pregnant, along with the fact that Cindy had slept with Junior as a substitute for George. The show confirmed in a Behind the Scenes video that the scene where the affair was revealed referenced both the "Sharongate" storyline, with the recording being played in a crowded pub. Following the affair reveal, Cindy was hit and knocked unconscious by an unseen figure with a shovel, with Junior being listed as an official suspect for his scorn against Cindy and being shunned by the family. The show later announced that the culprit for Cindy's attack would be revealed on the show's 40th anniversary.

On 28 October 2025, it was announced Balfour had been let go from the role. A spokesperson later revealed Junior would exit later that same year.

After a self-destructing George Knight (Colin Salmon) participates in underground boxing, despite being aware it could kill him as a result of CTE, his opponent is revealed to be his son Junior, causing George to opt out of the fight. Junior reveals he arrived due to his half-sister Anna Knight (Molly Rainford) contacting him as a last-ditch effort to stop their father's downward spiral. Despite this, Junior remains cold towards George and tells him he only arrived for the sake of his half-sisters Anna and Gina Knight (Francesca Henry). Junior sleeps with Bianca Jackson (Patsy Palmer), despite being married to Monique Knight (Busayo Ige). He soon introduces Monique and their son Xavier (Chase Dean-Williams) to the family and they bond. Junior and Monique's bliss is short-lived when Monique discovers that he has slept with Bianca, and she returns to Dubai with Xavier, having given Junior several chances to stop cheating in the past.