Early years A
centre back and occasional
right back, Mepham began his career in the
academy at
Premier League club
Chelsea at the age of 10. He was released at the age of 14 and was then turned down by
Watford and
Queens Park Rangers.
Brentford Youth years (2012–2016) Mepham joined the
academy at
Brentford in 2012, Mepham signed a scholarship deal in June 2014. After consistently good performances for the reformed
B team during the first half of the
2016–17 season, Mepham signed a two-year contract extension on 6 January 2017 and the following day, he made his senior debut as a late substitute for
Harlee Dean during a 5–1
FA Cup third round victory over
Eastleigh.
Breakthrough (2016–2019) After the departure of centre-back Harlee Dean on 30 August 2017, Mepham was promoted into the first team squad and signed a new five-year contract. He made his first start for the club in a 3–1
EFL Cup third round defeat to
Norwich City on 19 September 2017 and gave away the
penalty which led to the Canaries' opening goal. After appearing sporadically throughout the autumn, An achilles injury suffered by
Andreas Bjelland in mid-March allowed Mepham back into the team and he scored the first senior goal of his career with the equaliser in a 1–1 draw with
Sheffield United on
Good Friday. He finished the
2017–18 season with 23 appearances and one goal. During his two and a half seasons as a professional at
Griffin Park, Mepham made 48 appearances and scored one goal.
Bournemouth On 22 January 2019, Mepham signed a long-term contract with
Premier League club
Bournemouth for an undisclosed fee, Eight days later, he made his debut for the club as a substitute for
Junior Stanislas late in a 4–0 win over Chelsea. Mepham made a further ten appearances in the Premier League for the Cherries throughout the first half of the 2019–20 season, including a starring role in a 1–0 away win and clean sheet at Chelsea on 14 December. However, Mepham would suffer a "significant knee injury" in the FA Cup game against
Luton Town on 4 January, which would potentially rule him out for up to three months. in 2025
Sunderland (loan) On 30 August 2024, Mepham joined
Sunderland on a season-long loan. He made his debut in the 1-0 victory over
Middlesbrough on 21 September 2024. On 8 March 2025, Mepham scored his first goal for Sunderland, proving to be the winner in a 2–1 victory against
Cardiff, which was also his first goal for over four years.
West Bromwich Albion On 28 August 2025, Mepham signed for Championship club
West Bromwich Albion on a three-year deal for an undisclosed fee. He made his debut for the club on 30 August 2025, in a 1–0 win against
Stoke City. ==International career==