Debuting on the Music Box channel in 1987, he later presented BBC One's Blue Peter, and ITV's This Morning and the gameshow Wheel of Fortune.
Leslie spent his early years in the church choir, studied music on leaving school, and worked as a DJ in Copenhagen.
He played in goal for the Scottish team in the Celebrity World Cup Soccer Six tournament, which took place on 14 May 2006 at St Andrew's, the home of Birmingham City.
On his last show he was set John's Final Challenge which involved abseiling down BBC Television Centre, completing a velcro and wheelbarrow obstacle course, then trampolining and conducting an orchestra in the studio.
Leslie presented Blue Peter with Caron Keating, Yvette Fielding, Diane-Louise Jordan, Anthea Turner and Tim Vincent.
[citation needed] When Richard Madeley and Judy Finnigan departed the show in 2001, they were replaced by Coleen Nolan and Twiggy, with Britton and Leslie remaining on Fridays.
[10][11] However, Nolan and Twiggy proved less popular with viewers,[12] so Britton and Leslie took on the full job of presenting the show, bringing the ratings back up to around one million.
In 2002, after allegations of sexual offences were made in the press against Leslie, he was dismissed from the programme and replaced by Phillip Schofield from Mondays to Thursdays and by Eamonn Holmes on Fridays (with Ruth Langsford).
In November 2012, John Leslie began to present Friday's Drivetime show on 98.8 Castle FM, hoping to revive his career as a radio DJ.