|Born||10th September 1994|
|Residence||18a Victoria Street|
|Children||Joseph Brown (2011)|
|First appearance||30th July 2010|
|Duration||2010 to present|
|Number of appearances||224 (as of Episode 8148)|
|Played by||Georgia May Foote|
Katy Armstrong is a current resident of Victoria Street and has also lived at properties in Coronation Street. A daughter of Owen and sister to Izzy, she is currently in a relationship with Chesney Brown and gave birth to their son, Joseph on 23rd December, 2011.
Katy first met Chesney when Izzy invited her to his 16th birthday party in July 2010, and they immediately struck a chord. She later met up with him and he invited her to accompany him to the wedding of Roy and Hayley Cropper. She later moved into the flat next to the Builder's Yard with Owen in September 2010 and skipped a day off school to go with Chesney to the market where he worked. Owen was furious when he discovered this. Izzy also voiced her disapproval and opined that Chesney was a bad influence.
In October 2010, Katy and Chesney planned to have sex whilst Owen was out, although their plans were foiled when Owen decided to have a poker night in with some mates and they couldn't sleep together at Chesney's as his sister Fiz Stape was having a quiet night in with husband John. However, when Fiz and John decided to go out after watching a film, Chesney lost his virginity but was disappointed when Katy admitted that she had done it once before, but that it meant nothing. Owen was less than happy when he found out, and pinned Chesney against a wall telling him to stay away from Katy. He later talked to Fiz and John about his disapproval of Katy and Chesney sleeping together at 5 Coronation Street. Chesney decided to move out when Fiz banned Katy from coming round and Katy suggested they find a place of their own, but Owen forbade them from living together, but eventually gave his blessing to them staying at No.5.
Katy and Chesney moved out of No.5 and decided to move into 14a Victoria Street in March 2011 after Fiz said Schmeichel couldn't be in the house with baby Hope. An agitated Owen told their landlord that they had forged his signature in order to have them evicted. Katy then confessed to Izzy that she and Chesney had no choice but to run away, but Izzy told them she'd sign on their behalf to allow them to move in. Soon after moving in, they quickly developed money woes and Katy wanted to get a job immediately after finishing her GCSEs, but Chesney disagreed as did Owen.
Katy began to suggest to Chesney that they start a family together, and although unsure to begin with agreed to try for a baby. She soon fell pregnant and told Chesney, but didn't tell Owen. She received consolation from Anna Windass who told her she couldn't keep the baby a secret from her father for long. Katy's pregnancy also affected her exams as she spent much of exam time throwing up and couldn't focus on revision beforehand. Owen eventually found out after Anna's foster daughter Faye Butler overheard Katy talking about morning sickness and informed Owen, who received confirmation from Katy that she was indeed pregnant. Soon after, Chesney disappeared after John locked him up with Alan and Dorothy Hoyle in the Hoyles' cellar and Owen assumed he'd done a runner. Katy agreed to have an abortion but Chesney stopped her at the last minute after escaping.
Katy and Chesney moved back into No.5 later in the year but when Schmeichel fell ill with liver disease and cancer in November 2011, Katy pressured Chesney to recognise his priorities which were her and the baby and to do what was best for Schmeichel. Although determined at first not to let his faithful companion be put to sleep, he eventually agreed to say goodbye to his dog.
- The character was introduced as a family member for Izzy Armstrong and a potential love interest for Chesney Brown.
- Her mother has never been identified.