Euphorbia geroldii is a species of plant in the family Euphorbiaceae. It is endemic to Madagascar. Its natural habitat is subtropical or tropical dry forests. It is threatened by habitat loss.
Euphorbia geroldii is endemic to north-east Madagascar, found within the surrounding coastal forest of Iharanae (Iharana), in the Ambilobé region. The area of occupancy is below 1 km². The species is treated by habitat degradation, fire, habitat clearing for charcoal. Also known as Thornless Crown of Thorns, it is a much-branched, unarmed, semi-succulent shrubs to 2 m tall. Giving the right conditions E. geroldii produces a non-Stop show of bright glowing red flowers throughout the year.