The announcement came following a meeting between Roscosmos head Vladimir Popovkin and ESA chief Jean-Jacques Dordain in Moscow Friday.
"The sides consider this project feasible and promising," Popovkin's spokeswoman Anna Vedishcheva told RIA Novosti. "The sides are to sign the deal by year-end."
The final agreement on Russia's participation in ExoMars is expected to be signed in November "and by this date the sides should confirm their financing," a space industry source told RIA Novosti.
The ExoMars program to send an orbiter to Mars in 2016 and a robot rover two years later was a joint project of NASA and ESA, but NASA has scaled back its participation amidst budget cutbacks and will not provide its Atlas rocket for the mission launches.
Russian scientists and space officials have repeatedly hinted at their intention to join the project, offering to provide Proton carrier rockets for the launches in exchange for full membership in the mission partnership.
Russia's participation in the project was approved Friday by the space council of the Russian Academy of Sciences.