Registered Nurse Salary in Illinois. The average Registered Nurse Salary in Illinois (IL) is $66,260 which is just below the national average figures for RN’s. There are approximately 114,730 Registered Nurses employed in the state of Illinois across a wide range of industry sectors.urse Practitioner Salary in Illinois. The average Nurse Practitioner Salary in Illinois (IL) is $80,550 which is a bit below the national average wage for Nurse Practitioners. The latest figures show that there are 2,610 Nurse Practitioners employed in Illinois across a range of industries.