During the 2001–02 English football season, Gillingham F.C. competed in the Football League First Division, the second tier of the English football league system. It was the 70th season in which Gillingham competed in the Football League and the 52nd since the club was voted back into the league in 1950. It was Gillingham's second consecutive season in the second tier of the English football league system, to which the club had gained promotion for the first time in 2000.

Gillingham began the season with a 5–0 victory over Preston North End, the first time the team had scored as many goals in a game for nearly two years, and were in third place in the league table after three games, but then lost four consecutive games, including one in which they conceded five goals for the first time since 1998. A further losing run in September and October left the team in 20th place out of 24 in the First Division league table but improved results in November and December meant that at the end of the calendar year they were in 12th place. Although the team's results in the second half of the season were inconsistent and they failed to win two consecutive games at any point between January and April, they were again in 12th place at the end of the campaign, an improvement of one position on their first season in the First Division.

Gillingham also competed in two knock-out tournaments. In the FA Cup, the team reached the fifth round but then lost to Arsenal of the Premier League. They were also eliminated from the Football League Cup by a Premier League team, losing to Southampton in the third round. Gillingham played 52 competitive matches, winning 22, drawing 10, and losing 20. Marlon King was the team's top goalscorer with 20 goals. Chris Hope and Paul Smith made the most appearances, both playing in every one of the team's matches. The highest attendance recorded at the club's home ground, Priestfield Stadium, was 10,477 for a match against Portsmouth on 26 December.

Background and pre-season The 2001–02 season was Gillingham's 70th season playing in the Football League and the 52nd since the club was elected back into the League in 1950 after being voted out in 1938. In the 1999–2000 season, Gillingham beat Wigan Athletic in the Second Division play-off final to reach the second tier of the English football league system for the first time in the club's history. In the team's first season at this level, Gillingham were seen by pundits as likely to struggle in the First Division and potentially finish 22nd or lower out of 24 teams in the league table, which would result in relegation back to the third tier, but instead the team finished in 13th place.

Andy Hessenthaler was the club's player-manager, a position he had held since 2000. Richard Hill was assistant manager and Wayne Jones held the position of first team coach. Paul Smith was the team captain. Gillingham made only one new signing ahead of the new season: David Perpetuini, a midfielder, joined from Watford just two days before the first game of the campaign, for a transfer fee reported as £100,000. Three players left, including Nicky Southall, who was transferred to Bolton Wanderers of the FA Premier League. In his column in the first matchday programme of the season, written before Perpetuini was signed, Hessenthaler apologised to supporters for being unable to strengthen the squad and said that the club was finding it increasingly hard to compete for new players with other First Division clubs due to the wages which Gillingham could afford to offer.

Gillingham's first-choice kit consisted of shirts, shorts, and socks all in the club's traditional blue; the second-choice kit, to be worn when there was a clash of colours with the opposition and Gillingham were the team required by the rules of the competition to change, was all-yellow. The club announced a new sponsorship deal prior to the season, its most lucrative to date, with the ferry operator SeaFrance, as a result of which the company's name was displayed on the players' shirts. The team's preparations for the new season began with a trip to Barbados, where they played a friendly match against the national team, followed by further friendlies in the United Kingdom. Previewing the season, BBC Sport acknowledged that Gillingham had exceeded expectations in their first campaign in the First Division but predicted that the team had "a tough season in prospect" and that they would "find it more difficult [...] as other teams become aware of their strengths". The Independent contended that Gillingham's squad was weaker than in the previous season and forecast that they would finish in 21st place.

First Division August–December Gillingham's first match of the season was at their own ground, Priestfield Stadium, against Preston North End, who in the previous season had reached the final of the play-offs for promotion to the Premier League but been defeated. Marlon King, Gillingham's leading goalscorer in the previous season, was missing from the team as he had been given a two-match ban as punishment for offensive comments made to the referee during a game at the end of the previous season. Marcus Browning scored twice, his first goals for Gillingham after more than 40 games for the club, in a 5–0 victory for the home team. It was the first time Gillingham had scored more than four goals in a game since October 1999. Following a goalless draw away to Sheffield United, Gillingham won 3–0 at home to Barnsley, King scoring twice in his first start of the season. The result meant that Gillingham were third in the league table and were the only First Division team yet to concede a league goal. After this strong start to the First Division season, Gillingham lost their next four league games. The run began with a 1–0 defeat to West Bromwich Albion which was followed by a 2–1 loss to Portsmouth. On 14 September, the team lost 5–1 away to Bradford City, the first time Gillingham had conceded as many goals in a league game since December 1998. A 3–2 defeat at home to Wolverhampton Wanderers four days later, in which Gillingham were reduced to ten men when Barry Ashby was sent off, meant that Gillingham had slipped to 17th place in the table. The team's losing run in the league ended on 22 September with a 2–1 victory at home to Rotherham United, and they followed this with an identical result away to Grimsby Town; Chris Hope and King scored Gillingham's goals in both games. The wins took Gillingham back up to 11th place in the table, but they then again lost four consecutive league games.

The losing run began with a 2–1 defeat at home to Coventry City, after which Gillingham lost again at Priestfield to Norwich City on 13 October. In the latter game Simon Osborn, a midfielder newly signed from Port Vale on a free transfer, made his debut and Robert Taylor made the first appearance of a second spell at Gillingham. Taylor, a forward who had scored 39 goals in 70 games for Gillingham between 1998 and 1999, re-joined the club on a three-month loan from fellow First Division club Wolverhampton Wanderers. The team's losing streak continued with a 3–1 defeat away to Wimbledon on 20 October and a 2–1 loss away to Birmingham City three days later which left Gillingham in 20th place in the league table. Jlloyd Samuel, a young defender, joined Gillingham on loan from Aston Villa of the Premier League and went straight into the starting line-up for the home game with Walsall on 27 October, replacing the injured Adrian Pennock. Goals from Perpetuini and Guy Ipoua gave Gillingham a 2–0 victory, their first win for over a month. In their final match of October, Gillingham took a 2–0 lead over Burnley inside the first 15 minutes but then conceded two goals and the match ended in a draw. Gillingham's first match of November was away to Manchester City. Shaun Goater scored a hat-trick for the home team in a 4–1 victory; BBC Sport described City's performance as "90 minutes of utter domination" and said that they "found little opposition from Gillingham". The result meant that Gillingham were again in 20th place in the league table, just one point above the relegation positions.

The team's next two games ended in goalless draws against Crewe Alexandra and Watford. Having failed to score in over three hours of football, Gillingham scored three times in the first half against Crystal Palace on 21 November and secured a 3–0 victory. Steve Kember, Palace's caretaker manager, said that Gillingham could potentially have scored more goals and acknowledged that his team had failed to match Gillingham's level of physicality during the game. On 24 November, Gillingham won 2–1 away to Millwall, coming from behind with goals in the final ten minutes from Ipoua and King. Gillingham's players wore Millwall's second-choice shirts for the match as their kit manager had mistakenly packed the team's first-choice shirts, which were the same colour as Millwall's. Gillingham extended their winning run to three games with a 2–0 victory away to Stockport County on 27 November with goals from Iffy Onoura and King. Samuel made his final appearance for the club three days later in a 1–1 draw at home to Birmingham City; Shaw missed a late chance to score a winner but BBC Sport said that "a draw was the fairest result". Gillingham began December with a 2–2 draw away to Nottingham Forest with two goals from Shaw and extended their unbeaten run to eight games by beating Sheffield Wednesday 2–1 at Priestfield on 15 December, with all the goals being scored in the first 30 minutes. A week later, however, the run ended as Gillingham lost 4–1 to Barnsley, who had been in 22nd place in the table going into the game. Following a 2–0 victory at home to Portsmouth on 26 December which drew an attendance of 10,477, Priestfield's largest of the season, Gillingham's final game of 2001 was three days later against West Bromwich Albion, also at home. The away team were reduced to ten players after just four minutes when Tony Butler, a former Gillingham player, was sent off. Despite the numerical disparity, the score was level until Smith scored in stoppage time at the end of the game to give Gillingham a 2–1 win. It was the final match of Taylor's loan spell; in contrast to his first stint with the club he had failed to score a single goal. The result meant that Gillingham finished the calendar year in 12th place in the league table.

January–April