The Sony Ericsson Xperia mini (model ST15i) is an Android smartphone from Sony Ericsson, released in August 2011. The Xperia mini has a "mobile BRAVIA engine" driving a 320×480 pixels 3-inch (76 mm) capacitive touch-screen, a 1 GHz Snapdragon S2 processor, a 5 megapixel camera, 512 MB of onboard RAM, and comes stock with a 2 GB microSD card (compatible with up to 32 GB). The phone is one of Sony Ericsson's environmentally friendly "Greenheart" range, featuring devices made of recycled materials, longer battery life and low-energy chargers, as well as minimal use of paper through reduced packaging and the replacement of the traditional printed user manual with one stored on the phone.

The Xperia mini (st15i) runs Android 2.3 "Gingerbread" but can be upgraded to Android 4.0, "Ice Cream Sandwich." It was touted as being an ultra-small smartphone that still retained higher-end specifications and performance.