Aydın, M.2025-07-302025-07-3020250037-87122175-118810.5269/bspm.753152-s2.0-105018491099https://doi.org/10.5269/bspm.75315Relative controllability of linear and nonlinear fractional systems with time-variable delays in control variables for finite-dimensional spaces is considered. Sufficient and necessary circumstances for the controllability of a linear fractional system are offered. Employing Schauder’s fixed point theorem, sufficient circumstances for the controllability of nonlinear fractional systems are presented. © 2025 Elsevier B.V., All rights reserved.eninfo:eu-repo/semantics/openAccessControl DelayFractional Differential EquationsMittag-Leffler Matrix FunctionRelative ControllabilitySchauder's Fixed-Point TheoremArticle