Prior he had also done modelling work and played basketball in the Greek professional leagues where he won medals,[1] as well as majoring in computer technologies at American College of Greece.

Shortly after his appearance on Dream Show, he signed a contract with Sony BMG Greece and released his first CD-single in the summer of 2006 titled "Panda Mazi" (Always together).

Shortly after, he was booked by Sony BMG Russia to release an English album in all the ex-soviet countries in 2008, although this never materialized and his collaboration with the Russian branch was terminated.

In 2008, Kostas Martakis and Danish-Greek singer Shaya were chosen to record a Greek-language version of Right Here, Right Now from the soundtrack of the Disney film High School Musical 3: Senior Year.

[7] In June 2009, Martakis released a song as a digital download single titled "Pio Konta" (Come closer) composed by Swedish producers Holter & Erixson.

In March 2011, he traveled to Moscow to record the duet titled "Sex Indigo" with Russian pop star Diana Diez.

[8] In the lead up to the album's release, Martakis teamed up with MAD TV and Hellas On-Line (HOL) for a special web concert previewing is new songs on November 24, 2011.

[10] was held on February 8, 2012 in the Tae Kwon Do arena, the guest host being Martakis who shared the presentation with Viki Kagia and Maria Sinatsaki.

[12] He played the decadent rock star Roger Davis, telling the story of a group of marginalized young people, trying to survive in New York of the 90s, who suffer poverty, love, passion, rejection and loss.

The musical was directed by Themidos Marcelou and with the participation of the actors Ada Livitsanou, Antigone Psychrami, Aris Plaskasovitis, Vasilis Axiotis, Christos Georgalis, Themis Marsellou, Stergios Ntaousanakis, Indra Kein, Andreas, and Maria Vasilatou Kapatais.