Grindeanu's ouster was expected after Romania's ruling leftists withdrew support from the government and filed a no-confidence motion in parliament.
Romania's parliament toppled the government of Prime Minister Sorin Grindeanu on Wednesday, as expected, a senior ruling party official said.
"It [the no-confidence motion] passed," the official said after the vote.
Official data showed Grindeanu lost the vote 241-7.
The motion needed 233 votes to topple Grindeanu, who refused to resign last week after his ruling Social Democrat-led coalition withdrew its support for his cabinet.
The Social Democrats said Grindeanu was not implementing the coalition government's programme.
On Sunday, they filed a no-confidence motion in parliament, escalating a conflict which government critics say reflects internal rifts over anti-corruption policy.
The Social Democrat Party (PSD) and its coalition allies withdrew their support for Grindeanu, 43, last Wednesday, saying he has failed to implement the PSD's broad governing agenda since it won a parliamentary election last December.
Grindeanu refused to resign and was expelled from the party.
One of the EU's most corrupt states?
Independent observers said the PSD is likely unhappy with Grindeanu's failure to relax Romania's anti-corruption rules earlier this year and wanted to oust him to ensure a different premier does more to protect party seniors facing graft charges.
Romania is seen as one of the European Union's most corrupt states and Brussels has kept its justice system under special monitoring since its 2007 entry.
At stake could be the future of PSD leader Liviu Dragnea, who has received a two-year suspended sentence in a vote-rigging case and is now on trial in a separate abuse of office case.
After a recent constitutional court ruling, the government has to propose a cap on financial damages caused by abuse of office offences, a level which could be decisive in Dragnea's case.
"This threshold is among reasons why Grindeanu had to be removed," said political analyst Cristian Patrasconiu.
A push this year by Grindeanu's government to decriminalise several corruption offences triggered the biggest street protests in Romania since the collapse of Nicolae Ceausescu's communist rule in 1989.
The government was forced to rescind the decree, and its architect, Justice Minister Florin Iordache resigned, citing a need to appease public opinion but saying he had done nothing wrong.
"Clearly Grindeanu is perceived by PSD leaders as lacking a firm hand," said Marian. "So they are looking for a prime minister tough enough to handle and defuse any potential street protests [in the future]."