The right and centre said they were "consolidated" in a Senate majority while the Greens said they had enough seats to form a political group.
The right-wing and centre parties held onto their majority in France's Senate on Sunday, Senate President Gérard Larcher said.
Nearly half of France's 348 Senate seats were up for grabs on Sunday as an electoral college of roughly 92,000 vote to replace the Senators in 59 départements and four overseas territories.
Half of France's Senate is reelected every three years but this year, the reelection of six senators representing French citizens overseas will be delayed to 2021 due to the COVID-19 pandemic.
The Green Party, meanwhile, which won several of France's major cities in June's municipal elections, said they now had enough seats to form a political group in the Senate.
Green party Senator Esther Benbassa tweeted that the party could form a group after winning six seats in the election.
French President Emmanuel Macron's centre-right party, however, struggled to increase seats in the Senate, winning seven to add to the 13 they already have in the upper chamber.
Many expected the Republicans to keep their majority in the Senate. They went into the elections on Sunday with a majority of 144 seats and had 75 seats up for grabs. By Sunday evening, they had held onto at least 71 of those seats.
The conservative Republicans often support Macron's pro-business agenda and several members of the government came from the party, founded by Jacques Chirac in 2002, including current Prime Minister Jean Castex.
Although Macron's party La République en Marche has a majority in the National Assembly or lower house of parliament which has the final say on laws, the presidential party has just 23 seats in the Senate, of which 10 were up for reelection on Sunday.