Provisional designation is the naming convention applied to astronomical objects immediately following their discovery. The provisional designation is usually superseded by a permanent designation once a reliable orbit has been calculated. As of 2019^[update], approximately 47% of the more than 1,100,000 known minor planets remain provisionally designated, as hundreds of thousands have been discovered in the last two decades. The modern system is overseen by the Minor Planet Center of the International Astronomical Union.

The current system of provisional designation of minor planets (asteroids, centaurs and trans-Neptunian objects) has been in place since 1925. It superseded several previous conventions, each of which was in turn rendered obsolete by the increasing numbers of minor planet discoveries. A modern or new-style provisional designation consists of the year of discovery, followed by two letters and, possibly, a suffixed number.

For example, the provisional designation 1992 QB1 stands for the 27th body identified during 16-31 Aug 1992:

This scheme is now also used retrospectively for pre-1925 discoveries. For these, the first digit of the year is replaced by an A. For example, A801 AA indicates the first object discovered in the first half of January 1801 (1 Ceres).

Minor planets discovered during the Palomar–Leiden survey including three subsequent Trojan-campaigns, which altogether discovered more than 4,000 asteroids and Jupiter trojans between 1960 and 1977, have custom designations that consist of a number (order in the survey) followed by a space and one of the following identifiers:

For example, the asteroid 6344 P-L is the 6344th minor planet in the original Palomar–Leiden survey, while the asteroid 4835 T-1 (now 20936 Nemrut Dagi) was discovered during the first Trojan-campaign. The majority of these bodies have since been assigned a number and many are already named.

The first four minor planets were discovered in the early 19th century, after which there was a lengthy gap before the discovery of the fifth. Astronomers initially had no reason to believe that there would be countless thousands of minor planets, and strove to assign a symbol to each new discovery, in the tradition of the symbols used for the major planets. For example, 1 Ceres was assigned a stylized sickle (⚳), 2 Pallas a stylized lance or spear (⚴), 3 Juno a scepter (⚵), and 4 Vesta an altar with a sacred fire (). All had various graphic forms, some of considerable complexity.

It soon became apparent, though, that continuing to assign symbols was impractical and provided no assistance when the number of known minor planets was in the dozens. Johann Franz Encke introduced a new system in the Berliner Astronomisches Jahrbuch (BAJ) for 1854, published in 1851, in which he used encircled numbers instead of symbols. Encke's system began the numbering with Astraea which was given the number (1) and went through (11) Eunomia, while Ceres, Pallas, Juno and Vesta continued to be denoted by symbols, but in the following year's BAJ, the numbering was changed so that Astraea was number (5).