Authorities responded to a call just after 11 a.m. on East Florinda St. near 10th Ave. in Hanford.
They found the eight-year-old with multiple stab wounds to her chest and face, and the 35-year-old mother with multiple stab wounds to her face.
Police have arrested the mother's boyfriend, 33-year-old Alejandro Sanchez, in connection to the stabbing. Police are unsure of a motive at this time, and they add that he was wearing an ankle monitor related to a previous DUI arrest.
Police say there were a total of four children at the apartment when the stabbings happened, but only the 8-year-old was hurt.
The girl and mother were taken to Kaweah Delta Medical Center in Visalia and later transferred to Community Regional Medical Center in Downtown Fresno for further treatment.