The hunger strike, led by inmates in isolation at the state's Pelican Bay prison, had lasted about two months and involved 30,000 prisoners at its peak. About 100 inmates were still refusing meals when it ended, the Los Angeles Times reported.
The newspaper said several striking inmates were collapsing daily, with an official saying some refused to go to medical wards.
Inmate leaders said they had "suspended" their protest, the Times said.
"Our goal remains: Force the powers that be to end their torture policies and practices in which serious physical and psychological harm is inflicted on tens of thousands of prisoners, as well as our loved ones outside," protest leaders said in a statement released by Tom Hayden, a former state lawmaker who said he had advised inmates' attorneys on strategy.
Prison officials had maintained their solitary confinement policies are non-negotiable.