The Nigeria international player had fallen out of favour at Kazan, as he was not guaranteed regular playing time, following several setbacks by injury and resultant loss of form.
He was also recently ordered to train with the club's reserve team following a clash with a team-mate.
However, Martins has now signed a two-year contract with Spanish club Levante, who see him as an ideal replacement to Arouna Kone, who they lost to Wigan during the immediate past summer transfer window.
Martins contract at Rubin Kazan was supposed to expire next year, but both parties decided to decided to negotiate a mutual termination.
According the reports in the Spanish media, the former Inter Milan forward had to take a massive pay cut to complete the move to Levante.
Martins is expected to earn about €600,000 annually at the Apanish club, a short fall from the €2.2 million he was reported to earn at Rubin Kazan.