Barry joined Stephen Kenny's coaching staff in February 2021 for the FIFA 2022 World Cup qualifying campaign but will now move to Belgium ahead of the FIFA 2022 World Cup finals later this year in Qatar.
"I've thoroughly enjoyed my time with the team and really enjoyed working with Stephen and the entire backroom staff and players. I've been fortunate to work with some outstanding managers in my career and Stephen certainly falls into that bracket," said Anthony Barry.
"The opportunity to move on to Belgium and to have the chance to take part in the World Cup Finals was one I felt I couldn't turn down. Of course, I wish all of the team the very best of luck for the future."
"I'd like to thank Anthony for the positive contribution he has made over the past year with the players and staff alike," said Republic of Ireland manager Stephen Kenny.
"Anthony had a great rapport with the staff and players, he was thought-provoking, an exceptional coach and a joy to work with. We respect his decision and he leaves with our best wishes."