Leon Reid has been cleared to run for Ireland at next week's European Championships in Berlin.
The IAAF has granted the Bath-born sprinter his international transfer.
Reid's mother is from Belfast, but he represented Britain at junior and under-23 level.
He won the national sprint double over 100m and 200m in Santry at the weekend and was provisionally named in the 42-strong Irish squad to travel to Germany.
There were fears that his transfer would not come through in time, but his clearance has now been confirmed.
The 24-year-old won a 200m bronze medal at the Commonwealth Games last April, running for Northern Ireland.