The RHSI was founded as a charity in 1816 promoting and educating on all aspects of gardening in Ireland.

The inaugural meeting took place on 30 September 1816 at the Rose Tavern, Donnybrook, Dublin as a Horticultural Society of Ireland with the Earl of Charlemont as its patron and Francis Hetherington as its chairman.

After a number of shows in the intervening years, the society declined, and was re-established with a new committee in 1830.

[1] Its membership is made up of both professional and amateur gardeners.

[3] In November 2023 the RHSI announced an extraordinary general meeting to consider changing its name by dropping 'Royal' from the title.