Central midfielder Joe O'Brien-Whitmarsh has joined Northampton Town on a permanent transfer from Southampton. The 21-year-old has signed a three-year contract at Sixfields, with the deal including a fee and significant future-related clauses for Southampton. It is understood that a number of other EFL sides were interested in signing the Irishman. O'Brien-Whitmarsh, who spent pre-season with the first team and was part of a training camp in Germany, originally signed for Southampton from Cork City in January 2024. He later had a loan spell at Accrington Stanley for the second half of the 2024/25 season, scoring three goals in 13 appearances, and featured twice for the Southampton senior team. The Republic of Ireland U21 international, who has four caps for his country, has a current market value of €200k, according to Transfermarkt. During the 2025/2026 season, he scored seven goals and provided three assists in 28 appearances in Premier League 2, and also scored four goals with one assist in 23 Premier Division games.