Samuels, 42, retired from internationals in 2020 but the charges relate to his participation in a T10 league in the United Arab Emirates. He has since retired from all cricket.
Samuels was found guilty of breaching the Emirates Cricket Board's Anti-Corruption Code by an independent tribunal.
One of the charges was that he failed to disclose "the receipt of any gift, payment, hospitality or other benefit" that "could bring the participant or the sport of cricket into disrepute" said an International Cricket Council (ICC) statement.
Samuels, a top-order batsman who played a key role in the West Indies' two T20 World Cup triumphs in 2012 and 2016, played 71 Tests, 207 one-day internationals and 67 Twenty20s for the West Indies between 2000 and 2018.
"Samuels played international cricket for close to two decades, during which he participated in numerous anti-corruption sessions and knew exactly what his obligations were under the anti-corruption codes," said Alex Marshall, the ICC's general manager.
"Though he is retired now, Mr Samuels was a participant when the offences were committed.
"The ban of six years will act as a strong deterrent to any participant who intends to break the rules."