Falkirk Aged 16, Kingsley made his first-team debut for
Falkirk on 12 April 2011 in a 2–1 win versus
Partick Thistle in the
Scottish First Division. He sustained an injury in a
2011–12 Scottish League Cup tie against
Brechin City that kept him out of action for over three months. He returned to the starting line-up in a League Cup win against
Dundee United. In March 2013, Kingsley signed a new contract with Falkirk. Kingsley made his 100th appearance for Falkirk on 5 April 2014, in a 5–0 victory over
Cowdenbeath. He was also voted in to the SPFL Championship Team of the Year for season 2013–14.
Swansea City On 30 June 2014, Kingsley signed for
Swansea City on a three-year deal for an undisclosed fee. On 18 February 2015, Kingsley joined
English League One side
Yeovil Town on a month's emergency loan which was later extended until the end of the season. Kingsley played in numerous positions in his 12 appearances for the Glovers including
left-back,
centre-back and
midfield, and received praise for his versatility from Yeovil boss
Terry Skiverton. Yeovil were subsequently relegated to
League Two at the end of the season and Kingsley returned to Swansea City. Kingsley joined
English League One side
Crewe Alexandra on an emergency loan in August 2015. He made 12 appearances for them before returning to Swansea after the emergency loan expired in November. He made his Swansea City debut in their
FA Cup 3–2 defeat away to
Oxford United, on 10 January 2016. He made his
Premier League debut on 2 March 2016 in Swansea's 2–1 victory away to
Arsenal.
Hull City Kingsley moved to
Championship club
Hull City in August 2017 for an undisclosed fee. He was released by Hull at the end of the 2019–20 season.
Heart of Midlothian Kingsley signed a one-year contract with
Hearts on 6 October 2020. On 21 January 2021, Kingsley signed an 18-month contract extension with Hearts, keeping him at the club until the end of the
2021–22 season. He further extended his Hearts stay in January 2022, signing a three-and-a-half-year contract and keeping him at the club until the summer of 2025. He then further extended his contract on 6 August 2024 with a new three-year contract until the summer of 2027. Kingsley quickly became known as an efficient taker of the
direct free kick, scoring several long-range strikes for Hearts since joining. He scored what proved to be the match-winning goal in the semi-final of the
2021–22 Scottish Cup – an
Edinburgh derby against
Hibernian – from a 30-yard free kick, albeit assisted with a
wall pass from
Liam Boyce. ==International career==