Micromosaics (or micro mosaics, micro-mosaics) are a special form of mosaic that uses unusually small mosaic pieces (tesserae) of glass, or in later Italian pieces an enamel-like material, to make small figurative images. Surviving ancient Roman mosaics include some very finely worked panels using very small tesserae, especially from Pompeii, but only from Byzantine art are there mosaic icons in micromosaic with tesserae as small as the best from the Modern period. Byzantine examples, which are very rare, were religious icons. The best known shows the Twelve Great Feasts of the Greek Orthodox Church and is in the Bargello in Florence. Another is in Rome and was crucial in developing the iconography of the Man of Sorrows in the West.

From the Renaissance they began to be made in Italy, reaching the height of their popularity in the mid 19th century, when Rome was the centre of production; there was a Vatican Mosaic Studio from 1576, set up to create mosaic replicas of the altarpieces in St Peter's Basilica, which were being damaged by the humid conditions of the vast and crowded interior. They were popular purchases by visitors on the Grand Tour, easily portable, and often taken home to set into an object there. Typical scenes were landscapes of Roman views, rarely of any artistic originality, and the micromosaics were small panels used to inset into furniture or onto snuffboxes and similar objects, or for jewellery. Religious subjects were copied from paintings. The very smallest mosaic pieces come from works from the period between the late 18th century and the end of the 19th. Fortunato Pio Castellani (1794–1865) expanded the range of subjects in his work in the "archeological style", copying Roman and Early Christian wall-mosaics. It was even imitated by porcelain painters, who painted faint lines across their work to suggest the edges of tesserae.