Macken, who turns 27 next month, had previously played 27 minutes as a substitute for England's U20 side at the 1997 World Youth Championships, but has not figured at a higher level for the country of his birth. Under FIFA rules, players who have not played a full international game can opt to play for a different country, provided they were entitled to nationality of that country when they played at underage level.
Macken is eligible through the grandparent rule, made famous in the late 1980s by former Republic boss Jack Charlton. He already holds an Irish passport and expressed his delight earlier today on hearing the news.
"I'm just delighted to be selected for the Bulgaria game. It's an amazing honour for me and my family and I look forward to justifying my selection if given a chance in the game," said the Manchester-born player.
"I would like to thank Brian and the FAI for the manner in which they have pursued my case with FIFA. I have always had a desire to play for the country of my family background and nationality but until now have never been given the opportunity," he continued.
"I’m looking forward to joining up with what is a fantastic squad and over the next two years will be doing my utmost to establish my place in the team for the World Cup qualifiers."
Kerr spoke of his intent to add Macken to his pack when hearing of the former Preston favourite's desire to play for the Republic. "He has a good goal scoring record and links the play well from an attacking position. From our first meeting Jonathan’s Irish connections and links were very clear to me and his desire to be considered for our squad and to implement the process of clearing his eligibility has been impressive," said the Dubliner, "his clearance to play for us gives us another attacking option for the games we face over the next two years."
Macken joined City for a then club record £5 million in March 2002 and despite injury problems, including knee, hamstring and foot complaints last season, managed to score four goals from nine league and Cup starts. He underwent a double hernia operation at the end of last season.