Create your Illinois sublease agreement, and sublet your property. Rent your unit to a subtenant with a sublease agreement form.In Illinois, tenants generally have the right to sublease their apartment or rental unit unless expressly forbidden in their lease agreement. 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. In most of Illinois, leases can prohibit subletting. Failure to comply with a lease term that prohibits subletting can lead to eviction. Sample Illinois Agreement to Sublease. This resource provides an example of what a sublease in Illinois looks like. Download. 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. A Sublease Agreement is a rental contract between an original tenant and a subtenant.