Brighton & Hove Albion 2021–22: Breakthrough into senior team A youth product of
Charlton Athletic and
Benfica, Sarmiento signed for the academy of Premier League side
Brighton & Hove Albion on 2 July 2021. He made his professional career debut on 22 September, coming on as a 69th-minute substitute for injured
Alexis Mac Allister in the 2–0 home victory over
Swansea City in the third round of the
EFL Cup. Sarmiento made a
Premier League matchday squad for the first time on 2 October, remaining as an unused substitute in the 0–0 home draw against
Arsenal. Sarmiento made his first senior start on 27 October, playing 69 minutes of the penalty shootout loss away at
Leicester City in the EFL Cup. He made his Premier League debut on 27 November, coming on as an 82nd-minute substitute replacing
Jakub Moder in the goalless draw at home against
Leeds United. Sarmiento made his first Premier League start four days later, where he ultimately played just 13 minutes due to an injury in which he was replaced, in the eventual 1–1 away draw at
West Ham United. It was revealed his injury, which was to the hamstring, would require an operation with Brighton boss
Graham Potter hinting he would be back towards the end of February 2022. On 31 January 2022, he signed a new contract, committing a long-term future with Brighton signing on until June 2026. Sarmiento made his return to the matchday squad remaining as an unused substitute in the 2–0 home loss against
Tottenham Hotspur on 16 March. He made his first appearance since his injury on 2 April, coming on as an 88th-minute substitute in the 0–0 home draw against bottom side
Norwich City. Sarmiento replaced Moder who was subbed on five minutes previously but picked up an injury himself. At Albion's end of season awards in May, Sarmiento won the Young Player of the Season thanking everyone for his support adding, "My first season and making my Premier League debut were really special and I am honoured to win this award."
2022–23 Sarmiento made his first Premier League start of
the season on 3 January 2023, where he helped set up
Evan Ferguson's goal in the 4–1 away win over
Everton. On 4 February, Sarmiento came on from the bench and later assisted
Kaoru Mitoma's 87th-minute winner, the only goal of the game in the victory over
AFC Bournemouth.
2023–24: Loans to West Bromwich Albion and Ipswich Town On 21 June 2023, Sarmiento agreed a new contract until June 2027, with the option of an extra year for the club. He joined
Championship side
West Bromwich Albion on a season-long loan on 25 July 2023. He made his debut on the opening weekend of the season, coming on as a substitute in the 71st minute for goal scorer
Matt Phillips. However, Sarmiento nor West Brom could find the equaliser losing 2–1 away at
Blackburn Rovers. Sarmiento scored his first professional goal of his career on 26 August, after coming off the bench he sealed all three points, scoring the last in the 4–2 home win over
Middlesbrough. Sarmiento was recalled on 1 January 2024. On 3 January 2024, Sarmiento joined fellow Championship side
Ipswich Town on loan until the end of the season. Sarmiento became something of a cult hero during his stint at Ipswich, scoring a last-gasp winner against promotion rivals Southampton to put the race for Premiership football in Ipswich's hands.
2024–25: Loan to Burnley On 30 August 2024, Sarmiento joined
EFL Championship side
Burnley on a one-year loan deal.
2025–26: Loans to Cremonese and Middlesbrough On 1 September 2025, Sarmiento joined
Serie A side
Cremonese on a one-year loan deal. However the loan deal was cut short and subsequently on 27 January 2026, Sarmiento joined
EFL Championship side
Middlesbrough on a 6 month loan deal, with an obligation to buy, subject to terms of the agreement been met. ==International career==