Nsemi, a former member of parliament, has a strong following in western Congo and has been a thorn in the side of successive governments.
He was arrested in March 2017 after leading deadly protests against former President Joseph Kabila, only to be broken out of prison by his supporters two months later.
Police announced his arrest on Twitter in an operation on Friday, saying: "Mission accomplished, it's done."
Kinshasa police chief Sylvano Kasongo said several officers were injured in the raid. A Reuters witness said Nsemi's followers attempted to protect his house in the plush Ma Campagne neighborhood by throwing palm nuts at the police, who fired their weapons as they moved in.
It was not clear if there were any casualties among Nsemi's supporters and a BDK spokesman could not be reached for comment.
Congolese security forces killed more than 300 BDK members and bystanders in crackdowns on sometimes violent protests in 2007 and 2008, dumping their bodies in the Congo River or mass graves, rights groups say.
After escaping from prison in May 2017, Nsemi spent two years on the run before re-appearing at a news conference in Kinshasa last year, pledging to contribute to the development of the country.
He has remained in Kinshasa for the past year, sometimes lashing out at Tshisekedi and others with xenophobic slurs that accuse them of having ties to Congo's eastern neighbour Rwanda.
"He terrorised people here in the neighborhood. We are very happy with his arrest. He belongs in prison," a neighbour of Nsemi told Reuters.
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