John McLaughlin made his Liverpool debut at the tender age of 18 against Huddersfield, scoring twice. He had shown great potiental in the reserves and the coaching staff at Liverpool believed he was a star in the making, a skilful midfield maestro. Shankly even declared him "the best schoolboy prospect to be turned up for a very long time." Shankly eased him into the First Division scene by picking him for the final game of the 1969-70 season, away to Chelsea. Despite being only 18 years old when the following season opened, Shankly had enough faith in the slightly-built but skilful teenager to make him an important part of the club's midfield of the time and his faith was rewarded when McLaughlin struck two first-half shots into the Kop goal when Huddersfield Town visited Anfield for the second home fixture of the season.
McLaughlin played in 30 consecutive First Division games but then lost his place and only figured in three of the remaining 12 matches. This season turned out to be his only one as a regular during Shankly's rebuilding of his aging side. When Shankly had completed the transformation he was cast aside. He made the line-up for the opening day of 1971-72 but was only picked on 4 further occasions, with two of those being as substitute. The emergence of Brian Hall and the arrival of Peter Cormack made it increasingly difficult for John to break back into the first-team and it was no surprise when he was allowed to leave Anfield to have a loan spell on the South coast with Portsmouth. All hopes of a career on the south coast evaporated when a knee injury put him out of the game for good when he was only 24-years-old.