He first appeared in episode 5421, broadcast on 9 January 2017, transpiring to be a school friend of established character Shakil Kazemi (Shaheen Jafargholi).

Morris began filming in November 2016 and Keegan was introduced to become promenant in storylines focusing with other teenage characters, namely Shakil, Bex Fowler (Jasmine Armfield), and Louise Mitchell (Tilly Keeper).

Initially characterised as an arrogant and spiteful bully, Keegan's character became more sensitive and sympathetic throughout his time on the soap, particularly following the introduction of his family – the Taylors – in June 2017.

The actor sang praises of his co-stars before Keegan and Tiffany departed in episode 6453, broadcast on 17 March 2022, being given a rare happy ending to their story.

He soon establishes himself as a local menace after breaking Louise Mitchell's (Tilly Keeper) phone and repeatedly teasing her, stealing cigarettes from a shop, and annoying Denise Fox (Diane Parish) by trampling flowers in the gardens and insulting her, which results in her hitting him.

Keegan and Tiffany start a sandwich-making business, named "Butcher, Baker Sandwich Maker", in a van bought by his brother-in-law Gray Atkins (Toby-Alexander Smith).

Tiffany decides to move to Germany with her brother Liam Butcher (Alfie Deegan) and signs divorce papers before sending them to Keegan.

[6] After he was cast, Morris had Jamie Borthwick, who played Jay Brown, as a mentor on set,[6] whom he praised for being "very wise for such a young guy" and for giving "great advice".

Duncan Lindsay of the Metro explained: "Keegan began his life in Walford as an odious character but he has been developed a lot since then and despite maintaining his edge, his deep love for his family and the root of his acting out have been explored more".

[17] Laura Morgan of Digital Spy described Keegan as a "reformed bad boy", adding that he had "proven that he's rather a sensitive, caring soul under all that bravado".

[9] Morris opined that the bullying storyline was important to show on TV as it is a common experience and he disclosed that himself and Armfield were close in real life.

[22] When asked if Keegan deserved a comeuppance, Morris responded: "I feel like he needs to, but I think it would take a big character to test him.

[41] He confided in Karen that he made it up since her "fancied her"[41] and eventually owned up to his lies, but not before a distraught Louise had gone through a harrowing ordeal at the police station and been dumped by her boyfriend Travis.

[42] Louise had also since ended her friendship with Travis[17][42] before in December 2017, Morris expressed interest in the pair becoming a couple in the future, revealing that he had received many messages from fans who hoped the two would embark on a relationship, despite his character's "somewhat chequered past with Louise",[43] he hoped the writers would "give [viewers] what they want"[42] as well as finding it "a new and interesting dynamic" as it would be his first time acting in a relationship.

[4] David Brown of Radio Times opined that a relationship was "not beyond the realms of possibility" for the characters, despite admitting that Louise would need to be "pretty forgiving" for one to happen.

[31] As Louise grew closer to newcomer Hunter Owen (Charlie Winter) and "set her sights firmly" on him, Keegan would become "desperately" persistent in keeping her attention, but would be "heading for heartbreak".

[47] Set to air later in Spring 2018,[48] details surrounding the story involved both Keegan and Shakil being stabbed by a youth gang and left for dead.

[49] The upcoming storyline was teased to be "hard-hitting" and show Keegan and Shakil be attacked, as a way of depicting how wide the ramifications of knife crime were.

[47][49] Kinsella praised the show for tackling the issue, stating: "I commend the EastEnders team for choosing this storyline to portray the realities of knife crime.

[20] Later details presented Keegan tracking down Bruno and "would put his fate in Carmel's hands", to her horror as she would try convincing him "that more violence is never the answer".

[69] Executive producer Jon Sen described their developing relationship as "lovely" and "a wonderful dynamic", praising Morris and Smith's performances.

[83] Speaking on his departure, Morris stated: "After five beautiful years on this incredible show, I have made the tough decision to leave Walford and give Keegan Butcher-Baker some well-earned rest".

[82] Executive producer Kate Oates commented that Morris had been an "incredible asset" to the show, "not just as a brilliant actor, but as an amazing company member".

[98] The following year, Morris received another Inside Soap Best Actor nomination,[99] as well as another Best Serial Drama Performance at the 25th National Television Awards.

[100] Daniel Kilkelly of Digital Spy named Keegan's first scene "pretty memorable", wondering if his introduction was intended to serve as a foil to Shakil.

[15] Lindsay called the depth given to the Taylor family, particularly Keegan, "a well oiled soap trope and it seems to be paying off for this initially aggressive clan".

[7] Justin Harp of Digital Spy described the scenes where Keegan and Shakil were stabbed as "horrific" and "brutal", reporting shocked and disturbed reactions from Twitter users.

[106] Daniel Kilkelly of Digital Spy said both Morris and Jafargholi "put in their best ever performances" during the scene, explaining: "Their on-screen agony this week has been genuinely uncomfortable and distressing to watch – as it should be".

[107] He also said that "new layers to Keegan have been beautifully exposed by Zack", particularly "his explosion of angst in the wake of his fear he had killed someone" as it "was not just powerful but a really important performance given the spate of knife crime attacks in London".

[107] Kilkelly (Digital Spy) agreed, commenting "2018 has shown us what this talented young star is really capable of" as he "took centre stage" in the stabbing story.