A Republican-backed group called Fairness and Accountability in Redistricting opposed the new state Senate maps because Republicans stand to lose seats because of the state's shifting demographics.
They gathered signatures in an effort to put a measure on the ballot to overturn them, but the high court ruled that the new boundary lines should be used in the June primary and the November general election.
The court found that the maps were "clearly the most appropriate map to be used in the 2012 state Senate elections even if the proposed referendum qualifies for the ballot."
If Democrats gain enough seats, they can pass taxes on their own.
Peter Yao, the acting chairman of the newly formed citizens commission, called the court's ruling decision "a great victory for the people of California" and said it was important for the stability of the electoral process in the state.
"It is regrettable that these challenges, based on partisan self-interest, have cost precious taxpayer dollars to defend the work of the people's commission," said Yao, a Republican from Claremont.
Six of the seven Supreme Court justices were appointed by Republican governors. The exception is Justice Goodwin Liu, who was appointed last year by Gov. Jerry Brown.
The Associated Press contributed to this report.