Disclosed are a wristband and a wrist wearable device. The wristband includes a wristband body portion, a connecting portion, and a memory metal portion. One end of the wristband body portion is connected to the connecting portion, the connecting portion is connected to one end of a device body of a wrist wearable device, and another end of the wristband body portion is a free end. The memory metal portion is provided on the wristband body portion and has an arc-shaped memory state in a natural state, so that the wristband body portion is naturally maintained in an arc shape, and the wristband is naturally maintained in a wearing state.

Watch bands can be provided with an ability to dynamically adjust the fit of a watch against a wrist of a user. One or more of a variety of tensioners can be provided with a shape-memory alloy that responds to a stimulus to adjust a fit of the band. Such stimulus can be from user or actively applied by the watch.