Richardson was born in Moston, Manchester and had his first trial at Burnley at the age of eight. In November 2018, he raised eyebrows when he scored 5 goals against Crewe Alexandra on his debut for Burnley under-18's at the age of 15. A few months later in February 2019, once he had turned 16, he made his debut for the under-23 side managed by Steve Stone. He scored a hat-trick against Rochdale in the Lancashire Senior Cup semi-final, having come on as a substitute at half-time. He subsequently became a regular member of the under-23 squad for the remainder of the 2018–19 season, regularly playing against players many years older than him. Burnley made sure to tie Richardson down to a two-year scholarship in July 2019, amid interest from fellow Premier League side Tottenham Hotspur.
