Born in SFR Yugoslavia, Sadiku was raised in Sweden and started to play youth football with local club Hånger IF in Värnamo. In 2003, he joined the youth setup of IFK Värnamo, the town's biggest club.[2]
In 2011, led by head coach Jonas Thern, Värnamo finished 13th in the Superettan table. Sadiku made 29 league appearances, scoring twice, and appeared in both relegation play-off legs against Väsby United, which the club won by 3–0 on aggregate.[4][5]
Helsingborgs IF
On 20 January 2012, Sadiku transferred to Allsvenskan club Helsingborgs IF.[6] Two months later, he won the 2012 Svenska Supercupen with the club, through a 2–0 win against AIK.[7] As defending Swedish champions, Helsingborg finished 6th in Allsvenskan, in which Sadiku made 19 appearances.[4] Throughout the season, he also played five games in 2012–13 UEFA Champions League, before Helsingborg was knocked out in the play-off round by Celtic by 0–4 on aggregate.[8]
In 2013, Sadiku played 27 league games, scoring twice, as Helsingborg finished 5th in the Allsvenskan table.[9] Halfway through the 2014 season, after making 11 league appearances, Sadiku sought a move elsewhere and reportedly attracted interest from rivalMalmö FF.[10][11]
On 17 August 2016, Sadiku transferred to Kasımpaşa for a fee of €2 million, signing a three-year contract.[14][15] On 12 January 2019, Sadiku signed a new three-and-a-half-year deal with the club.[16]
Hammarby IF
On 18 February 2022, Sadiku signed a three-year contract with Hammarby IF in Allsvenskan, thus returning to Sweden after eight years abroad.[17] Sadiku featured in the final of the 2021–22 Svenska Cupen, in which Hammarby lost by 4–5 on penalties to Malmö FF after the game ended in a 0–0 draw.[18][19] In early July, Sadiku tested positive for COVID-19 and suffered from persistent symptoms that kept him sidelined for almost two months.[20][21][22] He ended the season making 21 league appearances, helping his side to finish 3rd in the 2022 Allsvenskan table.[4]