Watford On 6 May 2017, Pereira made his senior debut for
Watford in a 3–0 away defeat at
Leicester City, coming on as a substitute in the 83rd minute for
Mbaye Niang. Pereira was awarded the
Watford Young Player of the Season award for the 2016–17 season.
Atlanta United On 15 January 2019, Pereira signed with
MLS club
Atlanta United. He later joined the club's affiliate side
Atlanta United 2 and on 10 March 2019, made his debut for the side in the
USL Championship in 2–0 win over
Hartford Athletic. Pereira was released by Atlanta before the start of their 2020 season.
Luton Town On 3 November 2020, Pereira signed with
Luton Town and joined the U23 team after 11 months without football. On 8 October 2021, Pereira joined
National League side
Yeovil Town on a short-term loan deal. Pereira's loan with Yeovil Town was cut short after just one match after being recalled by Luton. On 4 January 2022, Pereira joined
League Two side
Bradford City on loan until the end of the season. The move was assisted by Pereira's Luton teammate
Carlos Mendes Gomes, who had been managed by Bradford City manager
Derek Adams at Morecambe. On 1 September 2022, Pereira returned to Bradford City on loan until the end of the
2022–23 season. On 1 September 2023, Pereira joined
EFL League Two club
Sutton United on a season-long loan. On 27 January 2024, he joined
National League side
Dagenham & Redbridge on a loan until the end of the season. In June 2024, he returned to
the Daggers on a season-long loan deal. On 9 May 2025, it was announced that Dion Pereira would be released by Luton at the end of his contract.
Crawley Town On 4 July 2025, Pereira signed for
EFL League Two club
Crawley Town on a free transfer. ==International career==