During the 1999–2000 English football season, Gillingham F.C. competed in the Football League Second Division, the third tier of the English football league system. It was the 68th season in which Gillingham competed in the Football League, and the 50th since the club was voted back into the league in 1950. The team started the season in poor form, failing to win any of the first five league games, but then went on a much-improved run and began challenging for promotion to the Football League First Division. Robert Taylor scored 18 goals in 19 games by November, after which he was signed by Manchester City for £1.5 million, a new record fee for Gillingham. On the last day of the regular season, the team had a chance to gain automatic promotion, but lost and instead had to enter the play-offs. After defeating Stoke City in the semi-finals, Gillingham beat Wigan Athletic in the final to gain promotion to the second tier of the English football league system for the first time in the club's history.

The 1999 Football League Second Division play-off Final was an association football match which was played on 30 May 1999 at Wembley Stadium, London, between Manchester City and Gillingham. The match was to determine the third and final team to gain promotion from the Football League Second Division, the third tier of English football, to the First Division. The top two teams of the 1998–99 Football League Second Division season gained automatic promotion to the First Division, while the clubs placed from third to sixth in the table took part in play-offs. Manchester City ended the season in third position while Gillingham were fourth. The winners of these semi-finals competed for the final place in the First Division for the 1999–2000 season. In the semi-finals, Gillingham defeated Preston North End and Manchester City beat Wigan Athletic.