Smithies joined the Bluebirds from QPR in June 2018, signing a deal at Cardiff City Stadium that runs until the summer of 2022.
A former England youth international, Alex began his professional career with his hometown side, Huddersfield Town, for whom he made a total of 275 appearances.
He tasted promotion to the Championship with the Terriers in 2012, notably scoring the winning penalty in their League One Play-Off Final shootout victory over Sheffield United at Wembley.
Alex moved on to QPR in August 2015 and would pull on their shirt 109 times, winning the Hoops’ Supporters’ and Players’ Player of the Season awards in 2016/17. After establishing himself as City's first choice 'keeper early in 2020, Alex was runner-up to Lee Tomlin in the club's 2019/20 Player of the Season vote.