His grandfather, John O'Connell (died 1741), was a captain in King James II's guard at Aughrim.

[1][2] He told the antiquary Charles Smith that "We have peace in these glens and amid their seclusion ... profess the beloved faith of our fathers".

He maintained a regular correspondence with his youngest brother Daniel Charles O'Connell, a French army officer, taking him in 1793 after his escape from revolutionary France.

O'Connell gave him a gift of 300 guineas which allowed Daniel Charles to settle in London and negotiate for the formation of the Catholic Irish Brigade.

Uninterested in high society and politics, O'Connell preferred to live in rural County Kerry in obscurity, amassing a fortune despite his generosity and hospitality.

He had composed his own epitaph: "the chief ambition of his long and prosperous life was to elevate an ancient family from unmerited and unjust oppression".