The 38-year-old has opted to call time on a stellar international career that has amassed 134 senior caps - which is a record total for the Women's National Team.
Byrne made her senior debut at the age of 16 in March 1996 and went on to have a profound impact on women's football in Ireland by becoming a role model for her performances on the pitch.
The Kildare native is also one of the most decorated Irish players at club level having won 11 English League titles and the UEFA Women's Champions League, amongst many other honours, with Arsenal Ladies.
Reflecting upon her career and the decision to step away, Byrne said: "It can only be a positive thing to look back on how many caps I got and how long I got to play at the highest level whilst representing my country.
"I have made some great friendships along the way, learned a lot from so many people, and I always loved being involved with the Ireland team. Unfortunately we never managed to qualify for a major tournament - we went close against Iceland in a play-off - but I'll treasure the memories and experiences of every time I played for Ireland.
"It's a great achievement to step down having broken the all-time appearance record, but it's time to give other girls an opportunity to stake their claim in the team. I'll miss walking out to represent my country and all of the friends that I made, but I'm proud of my time with the team."
Tony Fitzgerald, FAI President, hailed Byrne for her remarkable longevity at such a high level. "Emma has been a credit to Women's football for many years and she will be sadly missed as she prepares to hang up her gloves.
"To play for Ireland for such a long time and produce the type of performances that she did says a lot about Emma's desire to represent her country. She was someone who young girls looked up to and she will forever be remembered as one of Irish football's great servants."
John Delaney, FAI CEO, stated: "To pull on the Ireland jersey is a special thing, but to do it on 134 occasions is quite remarkable. Similar to Robbie Keane and Shay Given, who retired from international football last year, Emma has earned her right to be described as an Irish legend.
"Women's football has made huge strides in recent years and we continue to work hard to advance the game at all levels. For that to happen we need players, coaches, administrators and volunteers to have the same level of commitment that Emma showed over two decades with the Women's Senior Team, to help drive us forward.
"Emma was a fantastic goalkeeper and ambassador for the women's game. I would like to thank Emma for her tremendous service and wish her and her family the very best for the future."
Niamh O'Donoghue, Chairperson of the Women's Football Committee, said: "I'm sorry to hear of Emma's decision to retire from international football.
"From the time that she first burst onto the underage international stage at age 14 she has been a fantastic servant to the women's game, representing her country at every age level and winning multiple honours at club level.
"She has always been a tremendous role model for young girls and I wish her continued success in the game and look forward to seeing her contribute as a coach, educator and commentator in the future."
Colin Bell, Ireland WNT Head Coach, paid tribute to Byrne by saying: "I'd like to thank Emma for her professionalism and her contribution to the squad in the short time that I've been the Head Coach.
"Emma's achievements at international level are rarely seen in the game and for her to represent her country over the course of 21 years is something most of us can only dream of.
"As we head into a new qualification campaign for the 2019 FIFA Women's World Cup, I think the timing for her decision is correct. Going forward, Marie Hourihan will be the new No.1 but it's important we continue to see Amanda Budden and Amanda McQuillan progress and challenge for that spot."