High Desert State Prison officials say 29-year-old Anthony Alvarez Junior was attacked by two other inmates on Wednesday evening.
Staff immediately began live-saving measures on Alvarez, but he died from his injuries.
Officers recovered two inmate-manufactured weapons used in the attack.
They also placed the two suspects in restricted housing, pending the investigation.
They are identified as Luiz Alvarez from Santa Clara County and Vincent Martinez from Kings County.
Anthony Alvarez came to the prison in July 2021, sentenced to 10 years for attempted second-degree murder.