Alexey Navalny's supporters in Moscow gathered near the Kremlin and outside the FSB headquarter.
Russian police have so far detained over 5,000 people at rallies across the country in support of opposition leader Alexey Navalny, according to the OVD-Info monitoring group.
His wife Yulia Navalnaya has also been detained, Navalny's allies said on social media.
The rallies are part of a campaign to win the release of President Vladimir Putin's staunch opponent, who was arrested on January 17 after returning from Germany.
Navalny had been recovering there after being poisoned by a nerve agent in Russia.
The 44-year-old opposition politician accuses Putin of ordering his murder, which the Kremlin denies.
Navalny is accused of parole violations which he says are trumped up.
A court is due to meet next week to consider handing him a jail term of up to three and a half years.
Police detained people in protests held in cities across Russia's 11 time zones, according to the OVD-Info, a group that monitors arrests.
In the far eastern port of Vladivostok alone, more than 100 people were detained after protesters danced on the ice and rallied in the city center.
The city of Novosibirsk in eastern Siberia saw one of the biggest rallies, with thousands marching across the city chanting "Putin, thief!" in a reference to an opulent Black Sea estate reportedly built for the Russian leader that was featured in a widely popular video released by Navalny's team. More than 80 protesters were detained.
In Moscow, authorities introduced unprecedented security measures in the city center, closing subway stations near the Kremlin, cutting bus traffic and ordering restaurants and stores to stay closed.
Navalny's team initially called for Sunday's protest to be held on Moscow's Lubyanka Square, home to the main headquarters of the Federal Security Service, which Navalny claims was responsible for his poisoning. After police cordoned off the area around the square, the protest shifted to another central square a mile away. Police deployed in force at that location too, detaining scores and putting them into police buses.
As part of a multipronged effort by authorities to block the protests, courts have jailed Navalny's associates and activists across the country over the past week. His brother Oleg, top aide Lyubov Sobol and three other people were put Friday under a two-month house arrest on charges of allegedly violating coronavirus restrictions during last weekend's protests.
The protests following Navalny's dramatic return to Moscow despite the threat of arrest put Putin in a quandary over how to respond.
Polls show pent-up frustrations among Russians over years of falling wages and fallout from the pandemic.
The West has told Moscow to let Navalny go and his allies have appealed to US President Joe Biden to sanction 35 people who they say are Putin's close allies.
To galvanise support at home in an online video viewed over 100 million times, Navalny has accused Putin of being the ultimate owner of a sumptuous Black Sea palace, something the Kremlin leader has denied.
On the eve of the protests, Arkady Rotenberg, a businessman and Putin's former judo sparring partner, said he owns the property.
Police have warned that Sunday's protests have not been authorised and will be considered illegal and broken up as they were last weekend.
They have also said demonstrators could spread Covid-19.
Officers detained more than 4,000 people at last Saturday's rallies, according to a protest monitoring group.
Protesters in one city turned out in temperatures of -52 degrees Celsius.
In Moscow, police appeared to struggle to find enough jail space. One protester said authorities only found him a cell late on Wednesday after arresting him on Saturday.
This weekend, Navalny's supporters in Moscow plan to gather near the Kremlin administration and the headquarters of the FSB, the KGB's successor, where protesters in 1991 famously toppled a statue of the secret police's founder during the Soviet breakup.
Police said on Friday they would close seven metro stations and restrict pedestrian movement in the area due to the protest plans.
Many of Navalny's prominent allies were targeted in a crackdown this week. Several, including his brother Oleg, are under house arrest.