Pablo Rosas Hernandez, of San Jose, was arrested about 12:50 a.m. this morning in the city.
On Saturday at 7:35 p.m., firefighters responded to a report of an unresponsive baby at a home in the 400 block of Old Julian Street, police spokesman Dirk Parsons said.
The baby, identified by police as Anahi Hernandez, was transported to a hospital, where she later died.
The Santa Clara County medical examiner's office determined the baby had suffered blunt force trauma, Parsons said.
Hernandez is being held at Santa Clara County main jail.
The death marks the city's eighth homicide of the year.