The 30-year-old German, who had raced for the Banbury-based team since their debut in 2010, will leave the squad with immediate effect.
"Timo has made a very significant contribution to our team over the past three seasons, helping us to develop our package to the point where, for a large proportion of the 2012 season, we were holding 10th place in the constructors' championship," said John Booth, Marussia's team principal, on F1 website, hinting at economic reasons behind the split.
"Timo is a fantastic driver and he has been a very popular member of the team. Our team was founded on the principle of benefiting from proven experience whilst also providing opportunities for young emerging talent to progress to the pinnacle of motorsport," said Booth.
"Thus far, this philosophy has also been reflected in our commercial model. The ongoing challenges facing the industry mean that we have had to take steps to secure our long-term future. Tough economic conditions prevail and the commercial landscape is difficult for everyone, Formula 1 teams included."
Glock, who competed in 55 Grands Prix for Marussia with a best finish of 12th, was keen to pay tribute to the team.
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"I have had three excellent years with the Marussia F1 Team, during which I had the chance to actively participate in building and developing the team in its endeavours to succeed within the Formula 1 World Championship," he said.
"I am in fact very excited about what the future holds in terms of my own career and I hope to comment on that very soon."
Glock's departure leaves Marussia with rookie Max Chilton as their only confirmed driver for the 2013 season.
"We will provide an update regarding the completion of our driver line-up in due course," added Booth.
Marussia have also yet to confirm an unveiling date for their new car.