After spending time at Aris' academies, he played in the Greek third tier with Thyella Filota in 2015. Greek giants Olympiacos held talks with Stergiakis but the goalkeeper wanted first-team football and chose to go on trial with Slavia Sofia. Stergiakis joined Bulgarian Slavia Sofia in August 2015. He became the first choice goalkeeper for the U19 team and was an unused substitute in five matches during the 2015–16 season. In the beginning of August 2016 he was on trial in the Italian Roma.[citation needed] He travelled to Trigoria for a trial but turned down the offer to move to the primavera squad.[1]
On 21 August 2016, Stergiakis made his debut for Slavia coming as a substitute in the 74th minute in a 4–0 away loss against Levski Sofia.[2]
On 10 April 2017, Stergiakis was officially nominated for the 2017 Golden Boy Award, becoming only the second Greek footballer to receive such a 2017 nomination alongside Lazaros Lamprou.[3] After impressing the goalkeeping coach, Stergiakis signed a five-year contract.
On 29 June 2019, Stergiakis, was the only Greek player included in Tuttosport's list of the world's top-100 footballers at the U21 level.[4]
Blackburn Rovers
On 6 October 2020, Stergiakis joined Championship side Blackburn Rovers on a three-year deal, with the club having the option to extend the contract by a further 12 months.[5]
