Prosecutors say Oksana Makar was raped by three young men on March 9 in the southern city of Mykolaiv.
The assailants then tried to strangle her and set her on fire.
She survived but was hospitalized with severe burns and damage to her lungs.
Health officials in the eastern city of Donetsk, where she was treated, said she died on March 29 after battling for her life for nearly three weeks.
The crime shocked Ukrainians and sparked nationwide protests against corruption after police initially released two of the suspects whose parents were former regional government officials.
All three suspects were eventually arrested and charged with rape and one with attempted murder.