The state Senate voted 32-25 Tuesday to abolish the punishment. The House passed the legislation last week.
The landmark action comes more than a decade after then-Gov. George Ryan cleared death row and declared a moratorium on capital punishment in Illinois.
It's not clear what Quinn will do with the bill. The Chicago Democrat supports the death penalty but has continued the moratorium.
Critics say the state's capital punishment system is fundamentally flawed and point to Illinois' record of wrongly convicting innocent people.
Supporters of capital punishment say Illinois has created new safeguards. They also say execution should be kept as a deterrent and a bargaining chip to get confessions.