In Illinois, tenants generally have the right to sublease their apartment or rental unit unless expressly forbidden in their lease agreement. Create your Illinois sublease agreement, and sublet your property.Rent your unit to a subtenant with a sublease agreement form. An Illinois sublease agreement is a contract in which an existing tenant (sub-lessor) and a third-party (the sub-lessee) establish a rental arrangement. Clarify private housing applications and lease requirements, and discover safety tips for finding legitimate rentals. Sample Illinois Agreement to Sublease. This resource provides an example of what a sublease in Illinois looks like. Download. Have the landlord or the landlord's agent(s) write their name and sign the form in the spaces provided. You may use an extra sheet of paper as necessary. The subtenant agrees to assume all of the obligations and responsibilities of the sublessor under the original lease for the duration of the sublease agreement.