He was called to the national squad, making his playing debut in the 2–0 World Cup qualifying rounds victory against Albania in March 2005.

Bundesliga club VfL Bochum showed an interest in Gekas already by the spring of 2006, but Panathinaikos wanted €2 million for its forward.

During the 2006–07 season, VfL Bochum was fighting against relegation, but within a short period Gekas became one of the stars of the team and popular among fans.

Coach Marcel Koller described him in November 2006 as their "life insurance", since Bochum not only avoided relegation but secured their place in the Bundesliga quite a few matchdays before the last.

However, despite being the top scorer for Bayer Leverkusen in the 2007–08 season, Gekas was consistently dropped from the squad by coach Michael Skibbe, making mostly substitute appearances.

[7] On 11 April 2009, he came on as a substitute for one minute, replacing Jermaine Pennant in a 2–2 draw with West Bromwich Albion at Fratton Park[8] in his only Portsmouth match.

But in Leverkusen, he was competing with Stefan Kießling, Eren Derdiyok and Patrick Helmes for a place in the starting formation, and he failed to establish himself.

[15] On 25 January 2013, Gekas signed a one-and-a-half-year contract with Turkish Süper Lig side Akhisar Belediyespor, then struggling to avoid relegation.

On 5 September 2013, Gekas signed a one-year contract with Süper Lig club Torku Konyaspor, wearing the number 22 shirt.

[18] On 3 April 2015, despite the fact that Gekas had no injury problems and was the top scorer of the club, he was left out of the squad in a surprise move by manager Roberto Carlos.

[23] Six days later, in a Swiss Super League away win game against FC Zürich he made his debut with the club as a late substitute.

[29] On 29 October 2016, he netted two goals in his return in the first XI helping his club to reach a triumphic 5–1 home win against FC Lugano.

[31][32] On 20 February 2017, he scored his first goal in the league at the very late minute of the game, giving his club a crucial 3–2 away win against Denizlispor in their effort to be promoted.

On 19 March 2017, in a game against Şanlıurfaspor, he faced a dilatation joint in the medial side combined with damaged cruciate ligaments, thus forcing him to remain out of action for approximately 1–2 months.

[35] One year later, Gekas stated that it was a mistake for him to retire from the national team, thus making himself once again available to be selected by manager Fernando Santos.

[36] He was part of the Greek squad at UEFA Euro 2012, where he played in every match and scored one goal in a 2–1 loss against the Czech Republic in the group stage, as his country reached the quarter-finals of the tournament.

Gekas came on a substitute in the subsequent games against Japan (a 0–0 draw) and Ivory Coast (a 2–1 victory), putting Greece through to the knockout stage of the World Cup for the first time.

In Greece's round of 16 match against Costa Rica, Gekas came on as a substitute in the 69th minute and assisted Sokratis Papastathopoulos' 91st-minute equaliser with a shot that was parried into the defender's path by Keylor Navas.