He earned 26 appearances for Levadiakos, scored five goals and helping his team gain promotion to the Superleague Greece.

He scored his first goal for Levski on 27 August, netting the equalizer in the 1–1 away draw against BATE Borisov in the third qualifying round of the 2008–09 UEFA Champions League.

On 31 May 2009, in the penultimate game of the campaign against Minyor Pernik, Gadzhev scored his first league goal for Levski, clinching the draw 1–1 and the title for the club.

[5] A week later, he scored his first goal of the 2009–10 season, netting the fourth in a 4–0 win over Sant Julià in the 2nd Qualifying round of Champions League at Georgi Asparuhov Stadium.

He made his comeback for Levski from a serious knee injury on 16 March 2010, playing for 60 minutes as a captain of the reserves' 2–2 draw against Litex Lovech.

On 7 January 2016 he signed a pre-contract with the Russian team FC Kuban Krasnodar,[10] but 2 weeks later his contract was annulled due to the uncertain financial situation at the club.

[11] On 24 March 2016, after a successful trial period, Gadzhev signed a contract with English club Coventry City until June 2017.

[14] Gadzhev holds the record for the most red cards in The Eternal Derby of Bulgaria, having been sent off three times, though on two of these occasions it did not affect the proceedings on the pitch, as he was ejected from the bench as well as after the final whistle.