English-born Kiely played for England at under-15 (13 caps), under-16 (13 caps) and under-17 (four caps) levels. He made one appearance for Republic of Ireland B, starting in a 4–3 win over League of Ireland XI on 9 February 1999, in which he was substituted for Nick Colgan. He went on to represent the Republic of Ireland at full international level, earning his first cap as a substitute in a UEFA Euro 2000 qualifying play-off against Turkey in November 1999. He retired from international football in February 2003, but in April 2008 Ireland’s assistant manager Liam Brady suggested that Kiely could make a return to the squad. The rumours were then confirmed when he returned to the Ireland squad in Giovanni Trapattoni’s first squad as manager in May 2008. He won his first cap in five years when he appeared in the Republic’s 1–1 draw with Serbia that month, playing the full 90 minutes. On 28 May 2009, he walked out of the Ireland squad after Trapattoni informed him that he would be replacing Shay Given with Keiren Westwood for the second half of the friendly International against Nigeria at Craven Cottage on 29 May. He was capped 11 times by the Republic of Ireland, last appearing in 2008.