The Warriors guard collided with Aron Baynes and landed awkwardly on his left arm and wrist.
Curry held his arm in pain and left the court for the locker room shortly after with his side trailing 83-54 in the third period.
The Warriors confirmed during the final quarter that the two-time NBA Most Valuable Player had a broken left hand.
Curry will be out of action for an indefinite period, leaving the Warriors severely undermanned with Klay Thompson absent injured too.
Kevin Durant, who injured his Achilles during last season’s NBA Finals, has left the Warriors too.
The defeat is the Warriors’ third in four games, marking a poor start to the campaign for last season’s runners-up.
“Aron Baynes came up after the game and just wanted to know how Steph was doing,” GSW coach Steve Kerr said.
“You could tell he felt really bad. It’s just a random basketball play, so stuff happens.”
It is expected Curry will undergo scans tomorrow to determine the full extent of the injury.