Within its range, this is often one of the commonest butterflies, flying in gardens, woodlands, wasteland and arable land. It is surprisingly absent from large swathes of Europe, though, including the Rhône Valley in Switzerland and much of the Swiss plateau. In the Geneva region, however, it is often abundant and I have no idea what the reason for this discrepancy is. There are many apparently suitable places where it simply doesn't fly. Its common name comes from its habit of frequenting sunny gaps in hedgerows, so it is often seen around gates, though in truth it may be seen anywhere sunny near trees or bushes.

Males and females have an orange ground colour, broadly bordered with deep brown and with a twin-pupilled apical eyespot in each forewing. In addition, the male has a large and conspicuous sex brand beneath the cell of the forewing. The only really similar butterfly is the southern gatekeeper, which flies with the gatekeeper in much of its range. The male southern gatekeeper has a rectangular sex brand, obviously broken by orange along the veins. Both male and female southern gatekeepers have less extensive dark suffusion at the base of the upperside hindwing. The underside of the southern gatekeeper is very different, being rough-textured grey and brown with a large, white 'Y' shape formed by the postdiscal markings. That species also lacks the white-pupilled postdiscal spots found on the underside of the gatekeeper. The Spanish gatekeeper is even more distinctive, with white-pupilled black spots on the upperside hindwing of both sexes and in the male a large, dark basal area in the forewing, enclosing the sex brand. The underside of the Spanish gatekeeper is dark, with a single, angled, pale band and a series of orange-ringed, white-pupilled black spots.

Eggs are scattered by females in shady, grassy places and the caterpillars feed on various common species of grass. They hibernate while small, completing their development in the spring before flying in a single generation from July through to September.