After predictions Merrett would be drafted inside the top thirty in the
2013 national draft, In August, following Essendon's 87-point loss to the
Western Bulldogs in round 18, it was announced that he would miss the remainder of the season with a major stress fracture in his foot. In round 21,
2016, he became the third-youngest match-day captain in
Essendon history when he led the side against at
Etihad Stadium. Under his leadership, they won just their second match for the season, defeating the Suns by six points. He won the
W.S. Crichton Medal as the club's
best and fairest player for 2016, becoming the youngest player in 35 years to win the award. His magnificent season was capped off by polling 19 votes in the
2016 Brownlow Medal. This was the third-most votes for a player whose team won three or fewer games, and the most for a Bombers player since
Jobe Watson polled 30 votes (although Watson's award was later rescinded due to the
Essendon Football Club supplements saga). Merrett was named vice-captain for the
2017 AFL season. He had another fantastic season, collecting 659 disposals, receiving his first selection in the
All-Australian team, and being named vice-captain in the
22under22 team for the second year in a row. His 2018 season failed to reach the heights of his previous, after being concussed in the opening round against the
Adelaide Crows. He was continuously tagged throughout the year, but he showed signs of improvement as Essendon worked towards a resurgence. In January of the 2019 pre-season, Merrett injured his ankle, resulting in the use of a
moon boot for 2 weeks; however, he was available for selection in round 1. Merrett went on to return to near his best football during the 2019 season, which was capped off with a second club best and fairest award, comfortable surpassing new Essendon recruit
Dylan Shiel. The Essendon midfielder produced another brilliant season in 2020, averaging 26.3 disposals and 4.3 marks, a statistic ranked elite by Champion Data, in shortened quarters to finish second in the Crichton Medal. His 13 Brownlow Medal votes from 16 games, equal 11th overall, saw him rise to 12th position on the club's all-time votes leaderboard. Before the start of the
2021 AFL season, Merrett was re-added to the club’s leadership group with fellow Bombers
Michael Hurley,
Andrew McGrath and club captain
Dyson Heppell. This was after being removed from the club leadership in the 2020 season, which was seen by some as a surprising move. Merrett started the 2021 season in great form with 31 disposals and a goal in Essendon's round 1 loss to
Hawthorn. With injuries to key midfielders
Jye Caldwell and Dylan Shiel in Essendon's Round 2 loss to
Port Adelaide, much of the midfield load was placed upon Merrett. On 21 February 2023, Merrett was named the
captain of the Essendon Football Club, succeeding
Dyson Heppell. Merrett won the
Yiooken Award for his best-on-ground performance in Essendon's 1-point win over
Richmond in the 2023 edition of
Dreamtime at the 'G. In 2024, Merrett won the
Anzac Medal for his performance in the annual
Anzac Day match against Collingwood, in a match that was drawn. Merrett would also win the Crichton Medal, his 5th club Best and Fairest. At the conclusion of the
2025 season, it was reported that he had met with
Hawthorn coach
Sam Mitchell, in potential trade talks. Amid media speculation of his future at the club, Essendon president David Barham and coach
Brad Scott both stated that Merrett was contracted, and they expected him to remain at the club. Weeks later, Merrett won his sixth Crichton Medal, with uncertainty and controversy still hanging over his head. Ultimately, after tense negotiations during the trade period, Essendon refused to trade him and held him to his contract. Merrett subsequently resigned from his position as captain of the team, after returning for pre-season. ==Player profile==