The northern caracara has a length of 49–58 cm (19–23 in), a wingspan of 107–130 cm (42–51 in), and weighs 800–1,355 g (1.764–2.987 lb). Average weight is higher in the north of the range, smaller in the tropics. In Florida, 21 male birds averaged 1,117 g (2.463 lb) and 18 female birds averaged 1,200 g (2.6 lb). In Panama, males were found to average 834 g (1.839 lb) and females averaged 953 g (2.101 lb). Among caracaras, it is second in size only to the southern caracara. Broad-winged and long-tailed, it also has long legs and frequently walks and runs on the ground. It is very cross-shaped in flight. The adult has a black body, wings, crest and crown. The neck, rump, and conspicuous wing patches are white, and the tail is white with black barring and a broad terminal band. The breast is white, finely barred with black. The bill is thick, grey and hooked, and the legs are yellow. The cere and facial skin are deep yellow to orange-red depending on age and mood. Sexes are similar, but immature birds are browner, have a buff neck and throat, a pale breast streaked/mottled with brown, greyish-white legs and greyish or dull pinkish-purple facial skin and cere.
Adults can be separated from the similar southern caracara by their less extensive and more spotty barring to the chest, more uniform blackish scapulars (brownish and often lightly mottled/barred in the southern), and blackish lower back (pale with dark barring in the southern). Individuals showing intermediate features are known from the small area of contact in north-central Brazil, but intergradation between the two species is generally limited.