More than 1,000 kids participated in the corrections department's 12th annual "Get On the Bus" event in conjunction with the Center for Restorative Justice Works.
Thirty buses took the kids to state prisons including San Quentin, Solano State Prison, and Salinas Valley State Prison, the corrections department said.
"Uniting fathers with their children helps to keep the family bond that will encourage inmates to change their behavior when they are eventually released into society," corrections Secretary Matthew Cate said in a statement.
The buses arrived at 8 a.m. so the prisons could accommodate all the kids, many of whom see their fathers just once a year.
Last month, children were bused to the state's three women's prisons for the 12th annual "Get on the Bus Mother's Day" event.
The program provides travel bags for the children, comfort bags for their caregivers, a photograph of each child with his or her parent, and meals for the day.
Each child received a teddy bear with a letter from his or her parent, plus post-event counseling.
Donations from churches, schools, family foundations and other organizations fund the programs, and transportation is provided by Silverado Stages Inc.
About 200,000 children currently have an incarcerated parent in California.