Brunt, 33, made his international debut in 2004, and steps down having scored three times in 65 appearances.
The midfielder has revealed that a desire to help West Brom secure a return to the Premier League has played a key role in his final decision.
"After a period of lengthy consideration I have taken the difficult decision to retire from international football. I have spent a lot of time thinking it over but I feel, at this point in my career, I need my sole football focus to be on helping West Brom return to the Premier League," Brunt said in a statement released by West Brom.
"After 14 years of international football this also gives me the opportunity to dedicate more time to my family.
"The past six years, since Michael (O'Neill) has been our manager, have been the most enjoyable of my international career.
"It has always been an honour to represent my country but Michael restored pride following a difficult period for us as a team. He took us to a new level and for that I will always be grateful.
"I would also like to thank my teammates and all of the staff who have helped me over the years. A special thank you to the medical team who gave me so much support during our last campaign, especially after my knee injury.
"Lastly, but most importantly, I would like to thank the Northern Ireland fans, who have provided atmospheres I will remember for the rest of my days. It was always a pleasure to play in front of you. I look forward to returning to Windsor Park on your side of the white line."
Brunt missed out on representing Northern Ireland at Euro 2016 due to a knee ligament issue.