The 19-year-old left-back has signed a two-year contract.
He will join the Under-21 side preparing to open their league season at Crystal Palace on Monday.
Albion manager Andrew Crofts said: “He’s an exciting talent who can play at both ends and likes to attack.”
Samuels made 38 appearances for Reading in Premier League 2 last season and represented England at youth level through Under-17s.
Reading will receive compensation after Samuels turned down an offer of a professional contract this summer.
https://www.theargus.co.uk/sport/20602955.brighton-sign-imari-samuels-reading/?ref=rss Brighton sign Imari Samuels from Reading