Navalny - who was released Monday after serving 15 days in jail over last month's protests - urged citizens to rally on the country's June 12 Russia Day holiday for a new round of anti-corruption demonstrations.
"Let's go out on the streets on June 12 with our former slogans and under the national flag," Navalny wrote in an internet post.
"We have two months for preparations. We will attract more towns and gather more people."
Thousands of people nationwide took part in unauthorised protests Navalny organised on March 26 against alleged massive corruption by Prime Minister Dmitry Medvedev, one of President Vladimir Putin's most trusted allies.
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Kremlin critic Navalny gets 15 days in jail after protest
Navalny was among the roughly 1000 people detained at the demonstration in Moscow as police in riot gear cracked down harshly on the biggest show of opposition to the Kremlin in years.
Navalny - a populist with nationalist anti-immigrant views - has announced he intends to stand in 2018 presidential polls that are expected to see Putin cruise to a fourth term.
He faces legal obstacles to running for the top job due to a fraud conviction at a trial this year that would bar him from public office.
The 40-year-old anti-corruption crusader rose to fame with fiery speeches at mass protests over Putin's return to the Kremlin for a third term in 2012.
He has harnessed the power of social media and YouTube to spread his message and there were a striking number of teenagers at the March 26 protest who have grown up under Putin's rule.
Kremlin critic Navalny released from jail
"Hi everyone," Navalny wrote on Twitter, posting a picture of himself at the offices of his anti-corruption foundation after he was released from prison.
Just before his release when his sentence ran out at precisely 2.28pm local time (1128 GMT) police moved Navalny without warning to a different detention centre, in an apparent attempt to avoid media coverage.
The anti-establishment Kremlin foe was forced to hop on the metro as journalists and supporters were left waiting for him at the location where he had been held across Moscow.
The political and national mood has shifted since the protests, however, following a deadly bomb attack on the Saint Petersburg metro and the United States' direct intervention against Russia's ally Syrian President Bashar al-Assad
Medvedev rejects 'malarkey'
The latest protests focused on claims by Navalny's team of anti-corruption investigators that Medvedev controls luxury villas and vineyards through shadowy not-for-profit organisations.
The video report has been viewed more than 18 million times on YouTube and prompted wide discussion with mockery over details such as Medvedev's purchase of flashy trainers.
Medvedev finally responded in televised comments on April 4, rejecting the claims as "malarkey."
He accused Navalny of wanting "to try to pull people out into the streets and reach political ends," while following the Kremlin practice of not naming Navalny directly.
Following the protests, Putin accused "someone, some political forces" of trying to advance "selfish interests".
Navalny was fined for breaching rules of organising protests after going ahead with the Moscow protest without permission from the authorities.
Police searched the offices of his anti-corruption foundation and detained staff who were accused of disobeying police and sentenced to up to 10 days.
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