A channel cognitive wireless sensor system is proposed for low-power sensor network applications. Based on an RF spectrum sensing technology, the proposed receiver system is designed with channel-selective operation only for a valid input RF signal at a designated frequency channel. The new receiver architecture was implemented at the ISM band of 2.4-2.5 GHz. The system performance was evaluated by Bit-Error-Rate (BER) measurements with a data-rate of 64 kbps and a random data pattern of 2 ⁹ -1 for the sensitivity and selective receptions, respectively, in various multichannel environments. From the experimental results, the proposed system features excellent channel selectivity for the allocated channels.