Ferocactus peninsulae is a barrel cactus in the genus Ferocactus belonging to the family Cacteae.
Ferocactus peninsulae reaches a height of about 70 centimetres (28 in). This plant is oval to club-shaped and has 12 to 20 showy, deep ribs. The thorns are grayish-red and have a yellowish or whitish tip. The funnel-shaped flowers are red to yellow and reach a length of 5–6 centimetres (2.0–2.4 in). The fruits are spherical, yellow, up to 4.5 centimetres (1.8 in) long.