Wearable ultrasound has been widely developed for long-term, continuous imaging without the need for bulky system manipulation and repeated manual locating. To potentially lead to more accurate and reliable imaging monitoring, this work presents the design, fabrication, and evaluation of a novel high-frequency wearable ultrasound array belt (WUAB) for small animal echocardiography. The fabrication process involved precise dicing technology for a λ-pitch design. The 20 MHz WUAB consists of two matching layers, piezoelectric composite with 128 channels, customized flexible circuit substrate, acoustic backing layer, and customized belt structure with designed end tip and insertion point for wearability. The resulting WUAB demonstrates sensitivity of -5.69 ± 2.5 dB and fractional bandwidth of 57 ± 5 %. In vivo experiments on rat model showed expected echocardiography and B-mode images of rat heart. These results represent significant promise for future longitudinal studies in small animals and real-time physiological monitoring.