On 19 July 1820, Kelly was appointed by Pope Pius VII as the first bishop of the newly erected Diocese of Richmond in the United States.

Kelly sailed from Dublin on 9 October 1820, and arrived in New York, after sixty days at sea, on 24 December 1820.

[2] Kelly wrote about to his brother about the meeting with Maréchal :He did not receive me over kindly, and tried to persuade me it would be dangerous to take possession of my See; but his arguments did not satisfy me, and I arrived Norfolk on 19th January.

[5]In January 1821, Kelly took up residence in Norfolk, Virginia, which had a larger Catholic population than the episcopal see in Richmond.

To end the fighting, the pope appointed Kelly as bishop of the Diocese of Waterford and Lismore in Ireland on 9 February 1822.

[4] Writing to his brother in Ireland, Kelly had these thoughts:It does not appear to me a matter of very great importance whether I perform my pilgrimage through life on this side of the Atlantic or on yours, yet I must confess my own feelings and my knowledge of this country considered, I do give the preference to yours.