It happened around 3:45 Sunday morning on the 600 block of Carver Street in Lawncrest.
Authorities arrived to find Shawn Rodgers with a stab wound to the chest. He was pronounced dead at the hospital.
The girlfriend, 25-year-old Porchia Holloway, was taken into police custody.
Holloway has been charged with murder.
Police later learned the couple had an argument before the killing. The couple's child was home at the time but was not harmed.
There is no word what sparked the argument.