The fire broke out around 5:45 a.m. Saturday at the Legend Oaks Apartments, The Kansas City (Mo.) Star reported.
Deputy Fire Chief Craig Duke said when fire crews arrived, they found Brandi S. Johnson, 34, dead at the scene and Amiyah McClenton, 2, suffering from severe burns and smoke inhalation.
Amiyah died later at a local hospital. Johnson was watching her while her mother was at work.
The cause of the fire, which displaced 26 families living in the apartment building, is under investigation, Duke said.