Harratt played for junior club Upton United and was at the academies at
Barnsley and
Leeds United, before signing for
Huddersfield Town at under-17 level after impressing during a trial spell. Harratt joined
National League club
Harrogate Town on a one-month
loan starting on 17 January 2020. He picked up an
assist for
Alex Bradley on his first start for the club, in a 2–0 victory over
Eastleigh in the
FA Trophy at
Wetherby Road; manager
Simon Weaver stated that "his energy output and his movement caused Eastleigh a lot of problems... you can see he is going to get a lot of goals in his career". The loan was extended, though the
2019–20 season was curtailed early due to the
COVID-19 pandemic in England, and he returned to Harrogate for the play-offs in July. He was an unused substitute in the
play-off final at
Wembley Stadium, where Harrogate secured a place in the
English Football League with victory over
Notts County. He signed an extended
contract in December 2021, to keep him at the club until June 2025, with an additional year option. He joined
League Two club
Port Vale on loan on 7 January 2022, until the end of the
2021–22 season, where he would be reunited with former Huddersfield academy
coach Dean Whitehead. Huddersfield's Head of Football Operations
Leigh Bromby stated that "it was clear from our conversations how much they wanted the player and the role they envisage for him". He scored with a diving header on making his debut the following day, having come on as a substitute in a 4–1 defeat to
Premier League club
Brentford in an
FA Cup third-round game at
Vale Park. Manager
Darrell Clarke said after the game that "he has got a bit about him... we are really pleased and thankful to Huddersfield for allowing [the loan]". Harratt went on to also score on his league debut for the "Valiants" in a 3–1 defeat to
Swindon Town on 15 January. On 15 March, he came off the bench to score a brace in a 3–1 home win over
Mansfield Town, receiving a
booking for taking his shirt off during the first
goal celebration, and was compared to a young
Billy Sharp by acting manager
Andy Crosby. He started in the
play-off final at
Wembley Stadium as Vale secured
promotion with a 3–0 victory over
Mansfield Town; Michael Baggaley of
The Sentinel wrote that "The Stags defence couldn't handle him" and that he "put Vale in front with a diving header and was only denied a second by the
offside flag". On 2 June 2022, he returned to League Two after agreeing to join Huddersfield's
West Yorkshire derby rivals
Bradford City on loan for the entirety of the
2022–23 season. Manager
Mark Hughes said that: "Kian has a big personality and a real drive to succeed, so we are looking forward to seeing how he fares at
Valley Parade." He made his club debut as a substitute on 30 July and was
sent off deep into stoppage time following an altercation with
Doncaster Rovers goalkeeper
Jonathan Mitchell as Bradford recorded a 0–0 home draw. He received a three-match ban following the incident. He scored his first and only goal for Bradford in an
EFL Trophy tie against
Sheffield Wednesday on 30 August. His father spoke out on social media in September to complain of his son's lack of game time at the club. On 4 November 2022, Harratt's loan at Bradford was terminated and he returned to Huddersfield, following his criminal conviction for hare coursing. He scored his first goal for Huddersfield on 7 April 2023, scoring a late header in a 3–2 win away at
Watford. Manager
Neil Warnock described him as a "good lad" and challenged the player to establish himself in the Huddersfield first-team the following season. He signed a contract extension in August 2023, with sporting director
Mark Cartwright commenting that "his next challenge is to break into the first team on a more consistent basis". He scored two goals in 16 games in the
2023–24 season.
Fleetwood Town On 30 August 2024, Harratt returned to League Two on a season-long loan with
Fleetwood Town despite having featured four times for Huddersfield at the start of the
2024–25 campaign. On 7 January, the loan deal was made into a permanent transfer on undisclosed terms after he had registered three goals and an assist in 20 appearances.
Oldham Athletic On 11 March 2025, Harratt joined National League side
Oldham Athletic for an undisclosed fee, signing a contract until the end of the 2025–26 season. He scored the winning goal in extra-time of the 3–2 victory over
Southend United in
the final at
Wembley to secure the club a place back in the
English Football League. He scored hsi first goal of the
2025–26 season on 29 December, securing a 2–1 victory at
Walsall. On 24 January 2026, Harratt returned to the National League to join
Brackley Town on loan until the end of the
2025–26 season. Brackley went on to be relegated, with Harratt contributing one goal from eleven appearances. ==Style of play==