Anglerfishes display a wide range of body forms, from globose, almost spherical, to elongate, laterally compressed, or extremely dorsoventrally depressed. The head and mouth are typically large, the premaxillae protractile. The teeth in the jaws are numerous, small, villiform, in several rows, or very few in number and developed to form large fangs (as in most Ceratioidei). Vomerine teeth are usually present (absent in some Ceratioidei); palatine teeth are present or absent. The eyes are typically large (except in most adult female Ceratioidei). The anterior-most dorsal spine or illicium is nearly always present (but absent in male Ceratioidei and in both sexes of the ceratioid family Neoceratiidae), usually bearing a terminal bait or esca (absent in some Antennariidae, male Ceratioidei, and in both sexes of the ceratioid family Neoceratiidae). The esca is simple to highly complex, bioluminescent in nearly all female Ceratioidei. The bony support for the illicium (illicial pterygiophore), which lies within a shallow trough on the anterodorsal surface of the cranium, is highly protrusible in some taxa. The pectoral fins are highly modified, leg-like (except in Ceratioidei). When present, the pelvic fins are jugular in position and consist of 1 spine and 4 or 5 rays (pelvics are absent in Ceratioidei, except for larval Caulophrynidae). The gill openings are restricted to a small, elongate, tube-like opening situated immediately dorsal to, posterior to, or ventral to (rarely partly anterior to) the base of the pectoral fin. A pseudobranch is present or absent. A swimbladder is usually absent (present and physoclistous in some Antennariidae). The eggs are spawned in a double, scroll-shaped mucous sheath. The soft dorsal fin consists of 3-22 rays, the anal fin 3-19 rays, the pectoral fin 4-30 rays, and the caudal fin 8-10 rays.

The coloration of anglerfishes ranges from uniform gray, brown to black, without markings of any kind (e.g., some Lophioidei and Ceratioidei), to multicolored and complexly patterned (e.g., Antennariidae).

Typically small fishes, the largest known individuals of most families attain standard lengths of approximately 100-250 mm, but some (e.g., Lophiidae, some Antennariidae, Himantolophidae, Thaumatichthyidae, Ceratiidae, and Gigantactinidae) become much larger, lophiids exceeding a meter in length and a weight of 27 kg. Ceratioids display an extreme sexual dimorphism in which males are dwarfed, the largest known free-living individuals of most families measuring 10-30 mm SL (standard length), but reaching 40 mm SL in Himantolophidae; parasitically attached individuals usually range from about 7-30 mm SL, but reach nearly 120 mm SL in Ceratiidae.