|Date of birth||1 January 1988|
|Place of birth||Prague, Czechoslovakia|
|Height||1.80 m (5 ft 11 in)|
|2007||→ Kladno (loan)||17||(1)|
|2005||Czech Republic U17||2||(0)|
|2005||Czech Republic U18||5||(0)|
|2005–2007||Czech Republic U19||21||(0)|
|2007||Czech Republic U20||9||(0)|
|2008–2011||Czech Republic U21||18||(1)|
|* Senior club appearances and goals counted for the domestic league only and correct as of 22 May 2016.
Gecov began his club career with Slavia Prague at the age of six. The young midfielder went through all the youth teams of Slavia. He was 17 years old when he was promoted to the A-team. Gecov did not get a chance to make his debut in the Gambrinus liga for Slavia. In January 2007, Gecov was sent to SK Kladno on loan for the rest of the season.
Gecov made his debut in the Czech top flight in March 2007 against Tescoma Zlín. He started seventeen times for Kladno and scored one goal. In January 2008 Gecov signed a long-term contract lasting 3½ years with FC Slovan Liberec.
On 20 July 2011, Fulham announced the signing of Gecov on a two-year deal for an undisclosed fee. Gecov made his Fulham debut on Wednesday, 21 September in the League Cup against Chelsea at Stamford Bridge and he made his Premier League debut against Liverpool on 5 December 2011 at Craven Cottage.
Gecov has represented his country at all age levels. He was also a part of the Czech squad at the 2007 FIFA U-20 World Cup in Canada where he played six matches and helped the team to its second place. He represented Czech Republic under–21s at the 2011 UEFA European Under-21 Football Championship and was named in the team of the tournament. Gecov made his debut for the senior side on 10 August 2011 as a starter in the 0–3 loss against Norway in a friendly match.
- "Obchod se Slávií uzavřen" (in Czech). F.C. Slovan Liberec. 16 January 2008. Archived from the original on 20 February 2008. Retrieved 2 January 2014.
- "Gecov Signs". Fulham FC. Archived from the original on 30 July 2012. Retrieved 2 January 2014.
- "Gecov Departs". Fulham FC. Archived from the original on 26 July 2012. Retrieved 2 January 2014.
- "Gecov exchanges Gent for ex-club Slavia Praag" (in Dutch). sporza.be. 2012-12-21.
- "Marcel Gecov piłkarzem Śląska" (in Polish). 90minut.pl. Retrieved 7 July 2015.