Irish youth international Akachukwu, 19, heads out on loan for his first taste of senior English football, having joined Saints from Waterford in 2024.
Akachukwu made his senior debut for Saints in the 2024/25 campaign as a late substitute against Cardiff in the Carabao Cup, before becoming an Under-21s regular this season.
He was most recently on the bench for Tonda Eckert’s side in a 3-2 FA Cup win over Doncaster Rovers in January.
The teenager joins a Colchester side sat 11th in League Two, seven points adrift of the play-off places under Danny Cowley.
Akachukwu made 35 senior appearances for Irish club Waterford, scoring five goals, including a hat-trick in the League of Ireland play-offs.