The Dubliner made his debut against Northern Ireland in 2011 - and scored in the same game - before going on to become a key player at two UEFA European Championships (2012, 2016).
The Burnley defender, who has just worked his way back from injury, felt that it was the right time to call a halt to representing Ireland after becoming the 40th different men's senior player to earn 50 caps.
"It’s with a heavy heart that I have decided to retire from international football. To represent my country has been a dream come true and the biggest honour I could have had," said Ward.
"To play in a couple of major championships has been the highlight and the night we beat Italy at the 2016 EUROs will live with me for the rest of my life.
"I have been very proud to have played a part in those achievements and I feel this is a good time to move on. There are a lot of good young players and new talent coming through and I wish all of them, Mick [McCarthy] and the staff all the best for the future.
"I’d like to thank everyone – managers, players, backroom staff I’ve worked with and the supporters – and say it was a pleasure to work with each and every one of them."
Ward started 49 of his 50 games - coming on as a substitute in the 4-0 win over Oman in 2016 - and 33 of his appearances came in competitive games.
Ireland manager Mick McCarthy had included Ward in his provisional squad for the EURO 2020 qualifiers for Gibraltar and Georgia, but following a conversation the long-serving player opted to step aside for someone else to get an opportunity.
"I signed Stephen [Ward] first from Bohemians and worked with him at Wolves, and I'm kind of sad that I don't get to work with him with Ireland but he's made his decision and I can understand it," said McCarthy.
"He has had 50 caps and he can retire being proud of that achievement. I'm really proud to have worked with him because he was a really good player for me and for Ireland.
"Even though we bought Wardy as a striker, I remember the day that I put him at left-back, at Charlton Athletic, and he was outstanding, and I kept picking him there after that. He's had a really good career there and I'm sad to see him go but he wanted to be fair to me, fair to the other players, and fair to himself."
Now 33, Ward is still very much part of Burnley's first-team squad having joined the club in 2014. He previously lined out for Bohemians, Wolverhampton Wanderers, and a loan spell with Brighton & Hove Albion.
Stephen Ward International Career
Caps: 50
Goals: 3
Debut: v Northern Ireland, Aviva Stadium, May 24, 2011
First Goal: v Northern Ireland, Aviva Stadium, May 24, 2011
List of Games Played
24/05/2011: Ireland 5-0 Northern Ireland, Aviva Stadium
29/05/2011: Ireland 1-0 Scotland, Aviva Stadium
07/06/2011: Ireland 2-0 Italy, Liege
10/08/2011: Ireland 0-0 Croatia, Aviva Stadium
02/09/2011: Ireland 0-0 Slovakia, Aviva Stadium
06/09/2011: Russia 0-0 Ireland, Moscow
07/10/2011: Andorra 0-2 Ireland, Andorra la Velle
11/11/2011: Estonia 0-4 Ireland, Tallinn
15/11/2011: Ireland 1-1 Estonia, Aviva Stadium
29/02/2012: Ireland 1-1 Czech Republic, Aviva Stadium
26/05/2012: Ireland 1-0 Bosnia & Herzegovina, Aviva Stadium
04/06/2012: Hungary 0-0 Ireland, Budapest
10/06/2012: Ireland 1-3 Croatia, Poznan
14/06/2012: Ireland 0-4 Spain, Gdansk
18/06/2012: Ireland 0-2 Italy, Poznan
07/09/2012: Kazakhstan 1-2 Ireland, Astana
12/10/2012: Ireland 1-6 Germany, Aviva Stadium
14/11/2012: Ireland 0-1 Greece, Aviva Stadium
15/11/2013: Ireland 3-0 Latvia, Aviva Stadium
19/11/2013: Poland 0-0 Ireland, Poznan
05/03/2014: Ireland 1-2 Serbia, Aviva Stadium
25/05/2014: Ireland 1-2 Turkey, Aviva Stadium
31/05/2014: Ireland 0-0 Italy, Craven Cottage
10/06/2014: Ireland 1-5 Portugal, New Jersey
03/09/2014: Ireland 2-0 Oman, Aviva Stadium
07/09/2014: Georgia 1-2 Ireland, Tbilisi
11/10/2014: Ireland 7-0 Gibraltar, Aviva Stadium
14/10/2014: Germany 1-1 Ireland, Gelsenkirchen
14/11/2014: Scotland 1-0 Ireland, Celtic Park
08/10/2015: Ireland 1-0 Germany, Aviva Stadium
13/11/2015: Bosnia & Herzegovina 1-1 Ireland, Zenica
29/03/2016: Ireland 2-2 Slovakia, Aviva Stadium
31/05/2016: Ireland 1-2 Belarus, Turner's Cross
18/06/2016: Ireland 0-3 Belgium, Bordeaux
22/06/2016: Ireland 1-0 Italy, Lille
26/06/2016: France 2-1 Ireland, Lyon
31/08/2016: Ireland 4-0 Oman, Aviva Stadium
05/09/2016: Serbia 2-2 Ireland, Belgrade
06/10/2016: Ireland 1-0 Georgia, Aviva Stadium
09/10/2016: Moldova 1-3 Ireland, Chisinau
24/03/2017: Ireland 0-0 Wales, Aviva Stadium
04/06/2017: Ireland 3-1 Uruguay, Aviva Stadium
11/06/2017: Ireland 1-1 Austria, Aviva Stadium
02/09/2017: Georgia 1-1 Ireland, Tbilisi
05/09/2017: Ireland 0-1 Serbia, Aviva Stadium
06/10/2017: Ireland 2-0 Moldova, Aviva Stadium
09/10/2017: Wales 0-1 Ireland, Cardiff
11/11/2017: Denmark 0-0 Ireland, Copenhagen
14/11/2017: Ireland 1-5 Denmark, Aviva Stadium
06/09/2018: Wales 4-1 Ireland, Cardiff
List of Goals Scored
24/05/2011: Ireland 5-0 Northern Ireland, Aviva Stadium
15/11/2011: Ireland 1-1 Estonia, Aviva Stadium
31/05/2016: Ireland 1-2 Belarus, Turner's Cross