The bill would have created a new, smaller version of adult day health care for seniors and disabled adults.
Medi-Cal funding for the centers was slashed in the state budget.
Lydia Missaelides of the California Association for Adult Day Services says the veto brought up a range of emotions.
MISSAELIDES: "Concern ranging from anger to frustration to feelings of just being disrespected if you will be the state government."
Missaelides estimates that 95% of the centers may close and thousands of seniors could end up in nursing homes.
But Norman Williams of the California Department of Health Care Services says they have been working hard to find new options for the population, including in-home support services and coordinated care to keep people free of institutions.
WILLIAMS: "We're looking on a lot of options and just trying to find the right fit for each individual person based on their medical needs."
The state will continue paying for the service until December 1st.
Governor Brown approved a bill to allow centers to operate without Medi-Cal dollars.