Ardilaun was, like many in the Guinness family, a generous philanthropist, devoting himself to a number of public causes, including the restoration of Marsh's Library in Dublin and the extension of the city's Coombe Women's Hospital. In buying and keeping intact the estate around Muckross House in 1899, he assisted the movement to preserve the lake and mountain landscape around Killarney, now a major tourist destination. From 1875 he was a sponsor of the ""Dublin Artizan's Dwellings Company"", which built cottages for poor Dubliners at reasonable rents, and was the forerunner of the Iveagh Trust later set up by his brother Edward.