Watts, 26, was sent off in his side's defeat by Castleford Tigers on Sunday.
He pleaded not guilty to a Grade B high tackle charge and appealed after the original RFL panel ruled against him.
Meanwhile, Salford Red Devils winger Justin Carney, who faces a Grade F charge for verbal abuse based on race or colour, has had his case adjourned at the club's request.
However, the Devils have agreed that Carney will not play until his case is heard.
Hull FC prop Liam Watts has had his ban reduced from two games to one by the Rugby Football League.