A method and apparatus for performing cellular internet-of-things (CIoT) transmission in a wireless communication system is provided. A base station (BS) configures a frame in a CIoT carrier which is adjacent to a time division duplex (TDD) long-term evolution (LTE) carrier, and performs the CIoT transmission using the frame in the CIoT carrier. A downlink (DL) of the CIoT carrier may be adjacent to the TDD LTE carrier. Or, a DL and an uplink (UL) of the CIoT carrier may be adjacent to the TDD LTE carrier.