Last week Navalny and his Party of Progress joined ranks with the party of slain Kremlin critic Boris Nemtsov in a bid to form a democratic alliance after years of bickering.
"We are going to contest the polls," said 38-year-old Navalny, a lawyer who shot to prominence during mass protests against President Vladimir Putin in 2011-2012.
He said it was of paramount importance for "millions" of liberal Russians to win political representation.
Russian liberal parties failed to get into parliament in 2003 and have been marginalised ever since.
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Navalny, who has been fighting a series of criminal probes, cannot himself run for a parliamentary seat.
Ahead of the legislative polls the opposition would this year seek to contest local elections in three Russian regions and will conduct "primaries," he said.
"The best people will be included in the party lists," he said, speaking alongside Vladimir Milov, leader of the Democratic Choice party and several other figures.
The newly-established opposition alliance has been formed around the RPR-Parnas party of Nemtsov who was gunned down near the Kremlin in March in the most shocking assassination during Putin's 15-year rule.
Incensed by what they saw as mass violations during the last parliamentary polls, tens of thousands of Russians took to the streets in 2011-2012.
The rallies have since died down, with authorities jailing some opposition activists and forcing many others to flee.
Some liberal-leaning MPs were forced out of the parliament's lower house, the State Duma, while one dissenting lawmaker, Ilya Ponomaryov, has been forced to remain in the United States over fears for his freedom.
In 2013, Navalny ran for the post of Moscow mayor and came second with a stronger than projected 27 percent of the vote.