Boyd was transferred to boyhood heroes Celtic in an exchange deal which saw Tony Cascarino going to Chelsea. He played for Celtic for the remainder of his career, serving as club captain from 1997 to 2002. He holds the distinction of having been the captain who lifted Celtic’s first league title in 10 years in 1998, preventing bitter rivals Rangers from securing a record-breaking ten titles in a row.
As Boyd’s career moved on he began playing more in the centre of defence, whilst continuing to operate at full back on either side of the pitch when required, making him an exceptionally versatile defender. Boyd continued to captain the club after the arrival of Martin O’Neill at Celtic Park in 2000. In O’Neill’s first season in charge Boyd played a significant part in the securing of a domestic treble, only the third in the club’s history. Boyd became only the second Celtic captain (after Billy McNeill) to captain Celtic in a treble winning season. He also helped them win another Scottish Premier League title in 2001–02.