Galloway made his NRL début for the Cronulla-Sutherland Sharks in 2003 while still attending high school, a few months before his 18th birthday.
He made 8 appearances from the bench in the second half of the 2003 season, scoring a try in his second match.

Starting the 2004 season on the bench, Galloway scored the Sharks' sole try in the opening game of the season, a 6-12 loss to Wests Tigers.
He played in 14 games for the season, including some mid-season appearances in the starting side in the second-row.

Galloway was on the receiving end of a John Hopoate leaping elbow charge in 2005, leaving the 19-year-old unconscious on the field.
The event led to a 17-week suspension for Hopoate.
He was again a regular on the bench for the Sharks, but in the qualifying final match against St. George Dragons he was promoted to starting prop, in what was his last game for the club.
Galloway made his NRL début for the Cronulla-Sutherland Sharks in 2003 while still attending high school, a few months before his 18th birthday. He made 8 appearances from the bench in the second half of the 2003 season, scoring a try in his second match.
Starting the 2004 season on the bench, Galloway scored the Sharks' sole try in the opening game of the season, a 6-12 loss to Wests Tigers. He played in 14 games for the season, including some mid-season appearances in the starting side in the second-row.
Galloway was on the receiving end of a John Hopoate leaping elbow charge in 2005, leaving the 19-year-old unconscious on the field. The event led to a 17-week suspension for Hopoate. He was again a regular on the bench for the Sharks, but in the qualifying final match against St. George Dragons he was promoted to starting prop, in what was his last game for the club.
Keith Galloway