The 2018–19 season was Colchester United's 82nd season in their history and their third successive season competing in League Two. Along with competing in League Two, the club also participated in the FA Cup, EFL Cup and EFL Trophy.

Colchester missed the play-offs by just a single point in a dramatic season finale. Having been in and around the automatic promotion positions early season, Colchester found themselves fighting for the play-offs for much of the campaign. However, a drop in form in March going into mid-April saw them drop out of the play-off places and struggled to make a return. A short spell of form at the end of the season left them in contention with a game to spare, but an 87th-minute equaliser for Newport County in their game on the final day of the season meant the U's finished eighth.

In the FA Cup, Colchester were eliminated by League One side Accrington Stanley in the first round, and League Two rivals Cheltenham Town beat the U's following a penalty shoot-out in the first round of the EFL Cup. Colchester finished third in their EFL Trophy group, missing out on progression following defeats by Southampton under-21s and Cambridge United but did record an Essex derby victory against Southend United.

Season overview Preseason Colchester's position in League Two for the 2018–19 season was confirmed on 21 April 2018, when the U's suffered a 2–1 defeat at Lincoln City, mathematically ruling out potential for promotion through the play-offs.

On 8 May, following the conclusion of the 2017–18 season, Colchester announced four players would be leaving on 1 July 2018 following the expiry of their contracts. These included Doug Loft whose time with the U's had been plagued by injury, Scottish duo Denny Johnstone and Craig Slater who had both been on loan north of the border during the previous season, and Tommy O'Sullivan who again had been out on loan with Torquay United during the latter part of last season.

On 9 May, Academy graduate Drey Wright signed a two-year pre-contract agreement with Scottish Premiership side St Johnstone.

On 10 May, Colchester signed Cheltenham Town midfielder Harry Pell on a three-year contract for an undisclosed six-figure sum.

On 12 May, both Tom Lapslie and Brennan Dickenson took up the option of a further year on their contracts to remain with Colchester until summer 2019.

On 15 May, defender Ryan Jackson signed a contract extension with the club until the summer of 2020.

The club announced on 18 May that seven of the under-23 squad would be released at the end of their contracts. This included Tarryn Allarakhia, Charley Edge, Dominic Kurasik, Eli Phipps, Josh Pollard, Callum Sturgess and JJ Wilson.

Three scholars were offered professional contracts to remain with the club on 24 May, with Dean Ager, Callum Jones and Ollie Kensdale all offered terms.

On 24 May, Colchester signed goalkeeper Bailey Vose from Brighton & Hove Albion for an undisclosed fee on a two-year contract.

Following a successful trial towards the end of the 2017–18 season, Noah Chesmain agreed a one-year contract with the club on 25 May after his release by Millwall.

On 30 May, the club confirmed seven under-23s players had agreed contract extensions. These included George Brown, Ryan Clampin, Eoin McKeown, Decarrey Sheriff, Sam Warde, and Diaz Wright, who agreed one-year deals, and Louis Dunne, who signed a two-year deal.

On 1 June, the club announced that the new stadium sponsors would be JobServe and the stadium therefore renamed JobServe Community Stadium after the expiry of Weston Homes' ten-year deal. The same day, it was announced Millwall would be visiting the stadium for a pre-season friendly on 24 July.

Club captain Luke Prosser agreed a new two-year deal with Colchester United on 6 June.

On 7 June, Colchester signed former West Bromwich Albion goalkeeper Ethan Ross on a two-year contract, while Wolverhampton Wanderers forward Aaron Collins joined the club in a season-long loan deal.

On 8 June, Frank Nouble signed a two-year contract with the U's joining from League Two rivals Newport County after his contract had expired. Meanwhile, three more friendlies were confirmed, with trips to nearby Maldon & Tiptree and newly promoted National League side Braintree Town on 7 and 10 July respectively. Also announced was a trip to north Wales to play Colwyn Bay on 13 July.

On 12 June, a further friendly fixture was added with a trip to Dagenham & Redbridge set for 17 July.

On 15 June, Colchester were drawn away to Cheltenham Town in the EFL Cup first round.

On 22 June, Colchester announced another friendly game against Dartford on 21 July.

On 27 June, Colchester signed Swindon Town striker Luke Norris on a three-year deal for an undisclosed fee.

On 29 June, manager John McGreal announced that both Sean Murray and Sam Walker had left the club after failing to agree new contracts, while he also hoped out-of-contract Kane Vincent-Young would remain with the club.

On 5 July, Colchester signed centre back Chris Forino-Joseph on a one-year contract following a trial period with the under-23 side last season.

Colchester played their first pre-season friendly against Maldon & Tiptree on 7 July. The visitors in their new away kit took the lead through captain Luke Prosser when he headed in Aaron Collins' corner kick after 12-minutes. Three minutes later, Collins was again the provider for Sammie Szmodics to convert from close range. Collins was then fouled in the penalty area and stepped up to convert from the spot on 27-minutes. On the half-hour mark, Sam Warde, playing for the Jammers, scored for the home side with a 25-yard free kick. After the break, both sides made wholesale changes, and Mikael Mandron completed the scoring to make it 4–1 to United on the hour mark.

A final pre-season game against League One Gillingham was arranged on 10 July for Saturday 28 July.

Colchester travelled to Braintree Town for their second pre-season friendly. The U's took the lead after ten minutes when Frank Nouble registered his first goal for the club following a lay-off from Ryan Gondoh. In the second half the lead was doubled when Mikael Mandron struck on 51-minutes, before Sammie Szmodics scored four minutes later to make it 3–0. Junior Ogedi-Uzokwe scored from close range in the 71st minute and Mandron scored his third goal in two games to complete the scoring three minutes from time.

During their summer training camp in Cheshire, the U's faced Northern Premier League side Colwyn Bay. Two goals from Mikael Mandron and one each from Tom Lapslie, Aaron Collins and Frank Nouble secured an easy victory for Colchester.

Following the announcement that JobServe had gained the stadium naming rights, JobServe owner and club chairman Robbie Cowling announced JobServe would also be the club's shirt sponsor for home and away kits for the 2018–19 season.

On 13 July, Colchester were drawn against Southend United and Cambridge United for the EFL Trophy group stage, with their final Category One under-21 invited opponents revealed on 18 July.

Dagenham & Redbridge held the U's to a 1–1 draw at Victoria Road on 17 July. Michael Cheek opened the scoring with a free kick at the midway point of the first half, but Diaz Wright scored five minutes from full-time to rescue a draw for the visitors.

Colchester's final opponents in the EFL Trophy group stage were drawn on 18 July with Southampton under-21s set to visit the Community Stadium.

A late own goal proved the difference between hosts Dartford and the U's on 21 July. Ronnie Vint put the ball into his own net following a cross from Brennan Dickenson after 81-minutes as Colchester battled to a narrow victory over the National League South side.

In their penultimate friendly fixture and their first of two home friendly games, Colchester defeated Millwall 2–1 thanks to first-half goals from Sammie Szmodics and Kane Vincent-Young, still to sign a new contract with the U's. Millwall earned a late consolation goal through Jed Wallace in the 89th minute to deny United a clean sheet.

On 25 July, under-23s centre-back Will Wright signed for National League side Dagenham & Redbridge on loan until January.

On 27 July, Junior Ogedi-Uzokwe joined National League side Bromley on loan until January.

Colchester closed their pre-season campaign with a resounding 5–1 win over Gillingham at the Community Stadium. Sammie Szmodics opened the scoring inside five minutes. Szmodics then provided the assist for Aaron Collins to make it 2–0 after quarter of an hour, before Mikael Mandron made it 3–0 on 30-minutes. On 39-minutes, Gillingham's Mark Byrne received a red card for a challenge on Tom Lapslie. The visitors pulled a goal back just before the interval through Dean Parrett. Mandron restored the U's three goal advantage on 57-minutes, and Tom Eastman rounded off an unbeaten pre-season with Colchester's fifth goal on 62-minutes.

August Colchester United's League Two campaign started with an away game at Notts County on 4 August. John McGreal handed debuts to Harry Pell, Aaron Collins and Frank Nouble. Dillon Barnes was selected in goal for the U's and claimed a clean sheet for himself as the match ended 0–0, with both teams having good opportunities to take all three points.

After much speculation about his future, Kane Vincent-Young signed a new two-year contract with the club on 6 August.

On 7 August, the U's signed Dagenham & Redbridge academy player David Agboola to bolster the under-23 squad. He signed a one-year contract with the club.

Colchester faced Port Vale in their first home fixture of the season. Courtney Senior and Ryan Jackson scored in the eighth and 23rd-minutes respectively to hand the home side a 2–0 win on 11 August.

Colchester were once again eliminated from the EFL Cup at the first round stage. Hosts Cheltenham took the lead within the first minute through Ryan Broom following a defensive error by Frankie Kent. In the second half, Dillon Barnes conceded a penalty after a foul on Jacob Maddox. Conor Thomas stepped up to convert the kick and give Cheltenham a 2–0 lead. Substitute Sammie Szmodics registered his first goal of the season 12-minutes after arriving on the pitch in the 79th minute, before debutant Luke Norris scored to level the match at 2–2. The game ended in a draw, with a penalty shoot-out ensuing. Cheltenham won the shoot-out 6–5 after Courtney Senior missed the decisive kick in sudden death.

On 18 August, Colchester scored a 95th-minute equaliser in their game at Mansfield Town. Following a goalless first half, the hosts took an 81st-minute lead through Craig Davies, but Sammie Szmodics goal drew the U's level in the fifth minute of added time to secure a 1–1 draw.

On 21 August, Noah Chesmain signed for Southern League Premier Division Central side Hitchin Town in an initial month-long loan deal.

The U's hosted Crewe Alexandra in their first midweek fixture of the season on 21 August. Frankie Kent scored his first goal of the campaign after four minutes, before Brennan Dickenson scored his first goal since April 2017 to double Colchester's advantage just four minutes later. Dickenson then grabbed another goal on 26-minutes to give the hosts a 3–0 lead going in to half-time. After the break, Ryan Jackson scored his second goal of the campaign just before the hour mark, before substitute Luke Norris scored his first league goal for Colchester on 74-minutes. Tom Lapslie added another goal on 77-minutes to earn a comprehensive 6–0 victory for the U's.

Colchester suffered their first defeat of the season at home to Northampton Town on 25 August. A second-half goal from Matt Crooks was added to in injury time by Billy Waters but the U's earned themselves a late consolation goal after Aaron Pierre scored an own goal.

On 30 August, Tariq Issa signed for Southern League Premier Division Central side Needham Market on loan until January.