Published Wednesday, 28 March 2012
Horgan said he was "lucky" to have had a long injury-free career. (© Getty)
The 33-year-old Leinster three-quarter has not played for his province since their RaboDirect Pro12 final defeat to Munster at Thomond Park last May and has had to admit defeat in his efforts to make a return.
The Lansdowne FC product made his Leinster debut against Ulster in 1998 and over 13 years he made 207 appearances, scoring 71 tries, and won two Celtic League crowns and two Heineken Cups.
The powerful winger won 65 caps for his country, and played in the Triple Crown successes of 2004, 2006 and 2007 as well as the 2003 and 2007 World Cups.
He toured New Zealand with the Lions in 2005 and came on as a replacement in all three Tests as the series was lost 3-0.
He said: "Every professional sportsman realises that at some point their career will come to an end.
"I have been extremely fortunate to have played regularly for my province and with Ireland since my debut with Leinster in 1998 and while I am disappointed that injury has forced me to retire now, I know I have been very lucky to have had such a long and largely injury-free career.
"The support and expertise of the medical and fitness teams in Leinster and Ireland through the years has been first class. Their help, especially through the course of this injury, has been incredible.
"It has been a tremendous honour to represent my province and my country. When you first start playing sport that is the ultimate ambition but few people are lucky enough to realise it. I am just so grateful that I was given that opportunity.
"I am equally fortunate to have played at a time when Leinster and Ireland experienced such great success and alongside a group of players with unprecedented talent and ambition."
© Press Association